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Title: How to Collect and Preserve Insects
Author: Ross, H. H.
Language: English
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STATE OF ILLINOIS
DEPARTMENT OF REGISTRATION AND EDUCATION
HOW TO COLLECT
AND
PRESERVE INSECTS
H. H. ROSS
[Illustration: SEAL OF THE STATE OF ILLINOIS ★ AUG 26th 1818]
_Printed by Authority of the State of Illinois_
NATURAL HISTORY SURVEY DIVISION
George Sprugel, Jr., Chief
Circular 39 Urbana November, 1966
(Eighth Printing)
STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION
BOARD OF NATURAL RESOURCES AND CONSERVATION
John C. Watson, _Chairman_; Thomas Park, Ph.D., _Biology_; L. L.
Sloss, Ph.D., _Geology_; Roger Adams, Ph.D., D.Sc., _Chemistry_; Robert
H. Anderson, B.S.C.E., _Engineering_; Charles E. Olmsted, Ph.D.,
_Forestry_; W. L. Everitt, E.E., Ph.D., _Representing the President of
the University of Illinois_; Delyte W. Morris, Ph.D., _President of
Southern Illinois University_.
NATURAL HISTORY SURVEY DIVISION, Urbana, Illinois
SCIENTIFIC AND TECHNICAL STAFF
George Sprugel, Jr., Ph.D., _Chief_
Herbert H. Ross, Ph.D., _Assistant Chief_
Robert O. Watson, B.S., _Assistant to the Chief_
Section of Economic Entomology
William H. Luckmann, Ph.D., _Entomologist and Head_
Willis N. Bruce, Ph.D., _Entomologist_
Ronald H. Meyer, Ph.D., _Associate Entomologist_
James E. Appleby, Ph.D., _Associate Entomologist_
Robert D. Pausch, Ph.D., _Assistant Entomologist_
Ralph E. Sechriest, Ph.D., _Assistant Entomologist_
Delmar Broersma, Ph.D., _Assistant Entomologist_
Joseph V. Maddox, Ph.D., _Assistant Entomologist_
Edward J. Armbrust, Ph.D., _Assistant Entomologist_
Dannel McCollum, B.A., _Technical Assistant_
Gregory P. Marsh, B.S., _Technical Assistant_
Sue E. Watkins, _Junior Scientific Assistant_
H. B. Petty, Ph.D., _Entomologist in Extension_[1]
Stevenson Moore, III, Ph.D., _Entomologist in Extension_[1]
Roscoe Randell, M.S., _Technical Assistant in Extension_[1]
Clarence E. White, B.S., _Technical Assistant in Extension_[1]
Stanley Rachesky, M.S., _Technical Assistant in Extension_[1]
D. E. Kuhlman, M.S., _Technical Assistant in Extension_[1]
Amal C. Banerjee, Ph.D., _Research Associate_[1]
Jean G. Wilson, B.A., _Research Associate_[1]
Ranu Banerjee, B.A., _Research Assistant_[1]
Ayten Hatidoglu, B.S., _Research Assistant_[1]
Keun S. Park, M.S., _Research Assistant_[1]
Keturah Reinbold, M.S., _Research Assistant_[1]
Section of Faunistic Surveys and Insect Identification
H. H. Ross, Ph.D., _Assistant Chief and Head_
Milton W. Sanderson, Ph.D., _Taxonomist_
Lewis J. Stannard, Jr., Ph.D., _Taxonomist_
Philip W. Smith, Ph.D., _Taxonomist_
Leonora K. Gloyd, M.S., _Associate Taxonomist_
Wallace E. LaBerge, Ph.D., _Associate Taxonomist_
Robert T. Allen, M.S., _Technical Assistant_
Bernice Sweeney, _Technical Assistant_
Bess White, A.B., _Technical Assistant_
John D. Unzicker, Ph.D., _Research Assistant_[1]
Section of Aquatic Biology
George W. Bennett, Ph.D., _Aquatic Biologist and Head_
William C. Starrett, Ph.D., _Aquatic Biologist_
R. W. Larimore, Ph.D., _Aquatic Biologist_
David H. Buck, Ph.D., _Associate Aquatic Biologist_
Robert C. Hiltibran, Ph.D., _Associate Biochemist_
Donald F. Hansen, Ph.D., _Associate Aquatic Biologist_
William F. Childers, Ph.D., _Assistant Aquatic Biologist_
David L. Thomas, B.S., _Research Assistant_
Maryfran Martin, _Technical Assistant_
Claude Russell Rose, _Field Assistant_
Dennis Dooley, _Field Assistant_
Charles F. Thoits, III, B.A., _Research Associate_[1]
David Krulac, _Project Assistant_[1]
Section of Applied Botany and Plant Pathology
J. Cedric Carter, Ph.D., _Plant Pathologist and Head_
J. L. Forsberg, Ph.D., _Plant Pathologist_
Robert A. Evers, Ph.D., _Botanist_
Robert Dan Neely, Ph.D., _Plant Pathologist_
E. B. Himelick, Ph.D., _Plant Pathologist_
Walter Hartstirn, Ph.D., _Assistant Plant Pathologist_
D. F. Schoeneweiss, Ph.D., _Assistant Plant Pathologist_
David Russell Vance, _Technical Assistant_
Robert J. Slattery, B.S., _Technical Assistant_
Robert S. Perry, B.S., _Technical Assistant_
Betty S. Nelson, _Technical Assistant_
Sylvia P. Brockstein, M.S., _Technical Assistant_
Section of Wildlife Research
Glen C. Sanderson, Ph.D., _Wildlife Specialist and Head_
F. C. Bellrose, B.S., _Wildlife Specialist_
H. C. Hanson, Ph.D., _Wildlife Specialist_
Richard R. Graber, Ph.D., _Wildlife Specialist_
Ronald F. Labisky, M.S., _Associate Wildlife Specialist_
William R. Edwards, M.S., _Associate Wildlife Specialist_
William W. Cochran, JR., _Assistant Wildlife Specialist_
Robert E. Greenberg, M.S., _Research Assistant_
Helen C. Schultz, M.A., _Technical Assistant_
Lucinda Janis, _Technical Assistant_
Robert D. Crompton, _Field Assistant_
Ronald Duzan, _Laboratory Assistant_
Mary Ann Johnson, _Laboratory Assistant_
William J. Francis, Ph.D., _Research Associate_[1]
Jack A. Ellis, M.S., _Research Associate_[1]
James A. Bailey, Ph.D., _Research Associate_[1]
Gerald G. Montgomery, M.S., _Research Associate_[1]
William L. Anderson, M.A., _Research Associate_[1]
George B. Joselyn, M.S., _Research Associate_[1]
Gerald L. Storm, M.S., _Field Ecologist_[1]
Ronald L. Westemeier, B.S., _Research Associate_[1]
Stanley L. Etter, M.S., _Research Assistant_[1]
Robert E. Hawkins, B.S., _Research Assistant_[1]
Jeffrey C. Hanson, M.S., _Research Assistant_[1]
Keith T. Dauphin, _Project Assistant_[1]
Section of Publications and Public Relations
Owen F. Glissendorf, M.S., _Technical Editor and Head_
Robert M. Zewadski, M.S., _Associate Technical Editor_
Nancy K. Ginzel, B.S., _Assistant Technical Editor_
Wilmer D. Zehr, _Technical Photographer_
William L. Taylor, _Technical Assistant_
Technical Library
Doris F. Dodds, B.A., M.S.L.S., _Technical Librarian_
Patricia F. Stenstrom, B.A., M.S.L.S., _Assistant Technical Librarian_
CONSULTANTS: Herpetology, Hobart M. Smith, Ph.D., _Professor of Zoology,
University of Illinois_; Parasitology, Norman D. Levine, Ph.D.,
_Professor of Veterinary Parasitology and Veterinary Research,
University of Illinois_; Wildlife Research, Willard D. Klimstra, Ph.D.,
_Professor of Zoology and Director of Cooperative Wildlife Research,
Southern Illinois University_; Statistics, Horace W. Norton, Ph.D.,
_Professor of Statistical Design and Analysis, University of Illinois_.
[1]Employed on cooperative projects with one of several agencies:
University of Illinois, Illinois Agricultural Extension Service,
Illinois Department of Conservation, National Science Foundation,
United States Department of Agriculture, United States Fish and
Wildlife Service, United States Public Health Service, and others.
_This paper is a contribution from the Section of Faunistic Surveys
and Insect Identification._
(33711—10M—10-66)30
Where to Collect 1
What to Use 2
Nets 3
Killing Bottles 6
Aspirators or Suckers 9
Sifter 12
Berlese Funnel 12
Equipment for Collecting Aquatic Insects 16
How to Handle Unmounted Specimens 17
Temporary Cases 17
Relaxing Boxes and Jars 19
How to Mount and Preserve Specimens 20
Preservation by Pinning 20
Spreading Board for Moths and Butterflies 24
Preservation in Fluid 26
How to Label the Specimens 26
Housing the Collection Permanently 27
Insect Boxes 27
Precaution Against Pests 27
The Insect World 28
How to Identify Specimens 34
Synopsis of Illinois Insect Orders 35
Primitive Wingless Insects 35
Diplura 36
Protura 36
Collembola 36
Microcoryphia 36
Thysanura 38
Primitive Winged Insects 38
Ephemeroptera 38
Odonata 38
Folding-Wing Insects 40
Cursoria 42
Isoptera 43
Orthoptera 43
Dermaptera 44
Plecoptera 45
Zoraptera 45
Corrodentia 45
Phthiraptera 45
Mallophaga 47
Anoplura 47
Thysanoptera 47
Hemiptera 48
Megaloptera 52
Neuroptera 52
Coleoptera 53
Hymenoptera 54
Mecoptera 55
Trichoptera 57
Lepidoptera 58
Diptera 60
Siphonaptera 61
Relatives of Insects 62
Isopoda 62
Amphipoda 62
Scorpionida 64
Pseudoscorpionida 64
Phalangida 64
Araneida 65
Acarina 65
Diplopoda 66
Chilopoda 67
The State Insect Collection 67
Reports on Illinois Insects 69
Useful Books 70
How to Ship Specimens 70
Where to Buy Supplies 71
_Printed by Authority of the State of Illinois, Ch. 127. IRS, Par.
58.22._
[Illustration: Illinois streams are a source of many insects of
interest to the amateur collector. Shown here is the Salt Fork
River, south of Oakwood.]
HOW TO COLLECT AND PRESERVE INSECTS
H. H. ROSS
With rather simple equipment, the amateur as well as the trained
entomologist can make a worthwhile collection of insects.
The making of such a collection may have educational and recreational as
well as scientific values. Developing this hobby is one of the finest
ways for students, especially those in agricultural districts, to become
acquainted with the large number of injurious and beneficial insects
that they encounter about the home and in the fields. High school
classes in biology find excellent laboratory material in the many
insects available for rearing and study. Both old and young collectors
find a great deal of pleasure in working with the showy and beautiful
insects, such as beetles, moths, and butterflies; the satisfaction
derived comes both from having relaxation from the day’s work and from
making real contributions to scientific knowledge. Many entomological
museums welcome the opportunity to examine carefully prepared and
labeled collections. These collections supply distribution records for
insect species, in addition to other information of value to technical
entomologists. Also, the amateur collector profits from his contact with
specialists who can help him identify his specimens and advise him at
any stage of his work.
It is hoped that this circular will show how easy it is to make a start
in insect collecting and will give the student helpful ideas on how and
where to begin.
WHERE TO COLLECT
In late spring, in summer, and in early fall, insects are very abundant
in fields and woods, and large numbers of them may be caught by sweeping
through the grass and branches with a strong insect net. Flowers of all
descriptions are favorite visiting places of many bees, flies, beetles,
and other insects, and will afford good collecting. Woods along the
banks of streams, open glades in deep woods, and brush along forest
edges offer some of the best opportunities for collecting by the
sweeping method.
In early spring, when insects can be taken only sparingly in the open,
the collector frequently finds sheltered hollows where they may be
caught in large numbers. A certain kind of insect may live only on a
certain kind of plant, and to obtain the insect the collector must
search or sweep the plant, called the host plant.
Many obscure places harbor insects seldom found elsewhere. Among these
are leaf mold and debris on the surface of the soil, particularly in
woods; rotten logs and stumps, which should be turned over to reveal
insects that hide under or around them, and then carefully searched or
torn apart for others that live inside; in, under, and around dead
animals; under boards and stones.
Trees sometimes yield valuable specimens. If part of a tree, under which
has been spread a large white sheet, is struck with a heavy, padded
stick, many insects, such as weevils, will fall to the sheet and “play
possum.” They can be picked off quite easily.
Lights attract large numbers of certain nocturnal insects, such as June
beetles and many kinds of moths; at night these insects may be collected
at street or porch lights, on windows and screens of lighted rooms, or
at light traps put up especially to attract them. Swarms of aquatic
insects come to street lights of towns along rivers, sometimes in such
numbers as to pile up in a crawling mass under each light. Collecting at
this source is best on warm, cloudy nights; wind or cold keeps most
nocturnal insects fairly inactive. Different species of moths and
beetles visit the lights in different seasons so that collecting by this
method alone yields many kinds of insects.
Insects that live in the water may be collected with heavy dip nets
swept through the water at various levels and through the mud and debris
at the bottom. In shallow water, many insects will be found if stones
and logs are turned over and leaf tufts pulled apart.
In winter, insect galls or cocoons may be gathered. If these are placed
in jars with cheesecloth covers tied over them, kept in a warm room, but
away from radiators and all intense heat, many insects will emerge from
them before spring.
WHAT TO USE
For making even a fairly large insect collection, only a small amount of
equipment is required. A net and killing bottle are essential, and good
work may be done with these alone. A greater variety of insects may be
collected and with better results if a few more items are added to the
list. Here is an outfit that will be found very satisfactory in the
field.
1. A strong beating net for general sweeping and an additional light net
to be used for moths and butterflies.
2. Killing bottles, several small and one or two large ones.
3. A pair of flexible forceps, 10 to 12 centimeters (about 4 to 5
inches) long, with slender prongs.
4. One or two camel’s-hair brushes for picking up minute insects.
5. A few vials or small bottles containing fluid preservative.
6. Folded papers for butterflies.
7. A few small tins or boxes lined with cellucotton.
These items may be purchased from commercial supply houses such as those
listed on page 71. Many items, however, may be made by the collector at
nominal cost.
Nets
Nets are the most important items in the collecting kit of the
entomologist. For this reason nets should be rigidly constructed and
handled with care.
Construction.—Nets may easily be made at home. The necessary parts are a
handle, a loop or ring to be attached to it, and a cloth bag to be hung
from the loop, figs. 1 and 2. The handle should be strong and fairly
light. At the net end, fig. 1_a_, a groove is cut down each side to
receive the arms of the loop. The grooves are as deep as the thickness
of the wire used in the loop; one groove is 3 inches long and the other
2½ inches; and each ends in a hole through the handle at right angles to
the length.
The loop, fig. 1_b_, is made of steel wire, preferably
three-eighths-inch piano wire, which if bent by rough usage springs back
into shape and will stand a great deal of hard wear. The wire is shaped,
as the figure shows, to form a loop with two straight arms, the tips of
which are bent at right angles toward each other. The arms and hooks
thus formed must be exactly long enough to fit along the grooves and
into the holes in the handle. After the bag or net has been attached to
the loop, and the wire has been fitted to the handle, the joint may
either be wrapped tightly with wire, fig. 1_c_, or bound by a metal
cylinder or ferrule slipped over the arms of the loop, fig. 1_d_.
The bag, about twice as long as the diameter of the loop, should be
tapered at the bottom. It is made from four pieces of cloth, each cut in
the shape of fig. 2_a_, and a narrow strip or band of stout muslin or
light canvas, 2_b_, which is to bind the bag to the wire loop. The four
pieces are sewed together to form a cone-shaped bag, and one edge of the
band is sewed to the top edge of the bag.
The bag may be attached to the wire loop in either of two ways. The band
may be folded over the loop and sewed so that the attachment is
permanent; or it may be folded over, sewed, and then slipped on the loop
before the latter is fastened to the handle. In the latter case the bag
must be open along one seam just below the handle a sufficient distance
to allow the band to slip on and around the loop; this vent may be
closed with a string lacing after the net is on the loop, and the whole
fastened to the handle. A combination of this arrangement with a ferrule
binding the loop to the handle is most convenient, for it allows the bag
to be removed at will and a lighter or heavier one substituted according
to the needs of the collector.
[Illustration: Fig. 1.—Net loop and handle. The short grooves cut
opposite each other at the small end of the handle, _a_, end in
holes through the handle that receive the hooks of the loop arms,
_b_. The loop may be permanently bound to the handle with wire, _c_,
or a removable joint may be effected with a metal ferrule that can
be slipped up and down, _d_.]
[Illustration: Fig. 2.—Bag and completed net. The bag is cut from
four pieces shaped as in _a_, and the top edge of the bag is bound
with a narrow strip of stout muslin or light canvas, _b_, by means
of which the bag is attached to the loop. After the bag is on the
loop, the back vent may be closed with a string lacing, as shown in
the figure. This closing, which keeps the back of the net from
gaping, prevents the escape of the most active insects through the
back opening. The handle pictured here is a removable type, fig. 1
_d_.]
_General Purpose Net._—Loop, heavy wire, 12 inches in diameter; bag,
strong unbleached muslin or light duck, 20 to 24 inches long; handle,
hardwood stick, 24 to 30 inches long.
_Butterfly Net._—As above but with a longer handle and a bag of good
quality marquisette or fine nylon netting.
_Combination Net._—A net that includes the features and uses of the two
nets described above and is a better collecting instrument may be
conveniently made instead, although at slightly higher cost because of
the better materials. Its loop, of 7½ gauge (three-eighths inch) piano
wire, is 15 inches in diameter and allows a greater area to be covered
with each sweep. The bag, of finest bolter’s silk or best quality
marquisette, is 24 inches long and serves equally well for the capture
of delicate insects and for beating. The handle, of straight-grained
hickory or ash, is 40 inches long and permits the collector to cover
greater areas in sweeping. If a cheaper net is desired, one of
unbleached muslin will be satisfactory for general use.
Care and Use.—All nets are easily ripped and for this reason should be
kept away from barbed wire and from thorny trees, such as locust and red
haw. Also, they should be kept dry. Moisture rots the fabric, making it
more easily torn. Most insects caught in a net while it is wet are unfit
for a collection.
Flowers, herbs, and boughs should be swept with a sidewise motion. A
sidewise sweep will collect more insects than an upward or downward
sweep and at the same time mutilate less. If care is taken not to damage
flowers or foliage, the same patch of plants may be visited several
times with profit. The contents of the bag should be removed after every
few sweeps or strokes. This practice will prevent damage to the insects
caused by being jostled about in the net with a large amount of debris.
Killing Bottles
The best killing agents for use in bottles are either potassium cyanide
or calcium cyanide. These compounds give a concentration of deadly fumes
sufficient to kill most insects in a very short time, which is
desirable. Generally, two sizes of bottles are used, and in either of
them one of these cyanides may give good results. Only a small supply
should be purchased at a time, as they deteriorate rapidly.
Construction.—A pyrex glass test tube or strong ring-necked vial, about
three-quarters inch wide and 4 to 6 inches long, makes a good cyanide
bottle of the smaller size, fig. 3. Put about three-quarters inch of
granular potassium cyanide or calcium cyanide flakes in the tube or
vial. Cover with a tight plug of cellucotton, on top of which put one or
two loose plugs. Instead of cellucotton, you may use sawdust and a
plaster of Paris batter. In the latter case, cover the cyanide with
one-quarter inch of sawdust and over it pour one-quarter inch of newly
mixed, thick batter of plaster of Paris and water. Allow the batter to
harden for a few hours; then keep the bottle tightly corked except when
it is being used.
[Illustration: Fig. 3.—Cyanide killing bottles. The lethal chemical,
1, is potassium cyanide or calcium cyanide and is covered with a
layer of cellucotton, 2, or sawdust, 3, and plaster of Paris, 4. The
rest of the bottle is filled with soft, loosely crumpled, lint-free
paper, which should be changed whenever it gets damp. The bottles
should be tightly corked and labeled POISON. The collector should
_not_ test their strength by smelling.]
The larger cyanide bottle, fig. 3, which should be sturdy, may range in
capacity from one-half pint to a quart. _In the larger bottle, the
cyanide should always have the plaster of Paris covering._ The layer of
sawdust and plaster should be a little thicker than that for the smaller
bottle.
Care and Use.—Label all killing bottles and other containers of cyanide
conspicuously with the word POISON; keep them tightly corked and away
from children or adults who do not realize the extreme deadliness of the
compounds. _Never test the strength of a killing bottle by taking the
cork out and smelling the contents._ As an added precaution and
safeguard to the collector, tape the bottom of the cyanide bottle to
protect it against breakage.
The bottle should be almost entirely filled with loosely crumpled, soft
paper, which should be changed whenever it gets damp. This paper will
help keep the specimens from rubbing against each other inside the
bottle and thereby being damaged.
Each collector should have several cyanide bottles and follow carefully
these practices.
1. Transfer insects from net to bottle by holding the uncorked bottle in
a fold or corner of the net and crowding one or more of the specimens
into it, or “running” the open bottle up the side of the net beneath the
specimen or specimens. Most insects can be maneuvered into the bottle
easily and the opening temporarily closed by the thumb, or the stopper
can be put on. In obstinate cases, it may be desirable to stopper the
bottle through the cloth of the net until the specimen is stupefied,
after which the insect will drop to the bottom of the bottle.
2. Keep small, delicate insects in a bottle by themselves. Such insects
as large beetles are apt to mutilate small flies and other delicate
insects in the same bottle.
3. Keep a special bottle for moths and butterflies. When these die they
shed large quantities of scales, which stick to and partially spoil
other insects.
4. Keep the inside of the bottle dry. Cyanide bottles “sweat”; that is,
moisture both from the insects and the plaster condenses on the inside
of the bottle. Moisture will mat the hair and appendages of insects and
discolor the bodies. Do not crowd the bottle with large insects,
especially juicy ones like grasshoppers. Change the paper frequently.
Wipe out the bottle with paper or cloth, which should be carefully
disposed of in such a way that it cannot poison persons or pets. Keep
the killing chemical out of cuts and mouth. Wash hands with care after
handling the chemical.
5. Take insects out of the bottles soon after they are dead. Cyanide
fumes quickly turn many yellows to red or orange, and also make small
specimens brittle so that legs and other parts break off easily.
6. Empty the insects out of the bottles before they have accumulated in
a ball at the bottom. To do so will prevent damage to the smaller
specimens and discoloration due to “sweating.”
7. Dispose of a cyanide bottle when it will no longer kill insects
quickly. Substitute a fresh bottle and you will save time in the field.
Be sure to dispose of old bottles in such a way that their deadly
contents are out of reach of children and pets.
Aspirators or Suckers
Small, rapidly moving insects, such as leafhoppers, diminutive beetles,
and flies, may be collected by using an aspirator or sucker, figs. 4 and
5.
Construction.—An aspirator can be made from a capsule vial (available
from a drugstore) or from a piece of glass tubing. A small olive bottle
may be substituted for the vial.
The following items are needed for the vial aspirator, fig. 4: a vial,
1¼ inches in diameter and 3 or more inches long, a two-hole rubber
stopper with openings to fit one-fourth-inch diameter glass tubing, 16
inches of one-fourth-inch diameter glass tubing, rubber tubing 24 inches
long to fit over the glass tubing, a small metal file (the triangular
type is best), a small piece of cheesecloth, some string, and a bunsen
burner. Construct the vial aspirator according to the following
directions and as shown in fig. 4.
1. Cut the glass tubing into three pieces, 3 inches, 8 inches, and 5
inches in length. To cut the tubing, score it with an edge of the metal
file; then hold the tubing with both hands so that the thumb of each
hand is on the side of the tubing opposite to the scored mark; break the
tubing away from the body by exerting pressure with the thumbs.
2. Make a slight bend in the center of the 8-inch piece of tubing and a
right angle bend in the 5-inch piece, as follows: hold one piece of
glass tubing with both hands and place the center of it in the blue
flame of the bunsen burner; rotate the tubing slowly. When the glass
glows yellow, it begins to soften. Bend the tubing to the desired angle.
Then quickly withdraw the tubing from the flame.
3. Heat one end of the 8-inch piece of glass tubing in the bunsen
burner, slowly rotating the tubing so that the sharp edges melt slightly
and round out; then allow the tubing to cool. Heat one end of the 3-inch
tubing in the same manner. Smooth the remaining rough edges of the glass
tubing by heating them slightly.
[Illustration: Fig. 4.—Vial type of aspirator or sucker. End _g_ is
placed in the mouth; _c_ is used to pick up the insects. Shown also
is a cyanide cork, _h-i_, which is used to kill insects in the
aspirator.]
[Illustration: Fig. 5.—Tubing type of aspirator. Parts for this
aspirator should be compared with equivalent parts for the aspirator
shown in fig. 4. Noted especially should be the position of the
glass tube, _c_, and the length of the rubber tube, _f_.]
4. Insert the 8-inch and 5-inch pieces of glass tubing into the rubber
stopper. The longer piece, fig. 4_c_, should project about 1½ inches
into the vial. The shorter piece, fig. 4_d_, should project about
three-fourths inch.
5. Over one end of the 5-inch piece of glass tubing, fig. 4_e_, tie two
thicknesses of cheesecloth securely with string.
6. Over the other end of the 5-inch piece, slip one end of the rubber
tubing, fig. 4_f_.
7. Into the other end of the rubber tubing slip the 3-inch piece of
glass tubing, fig. 4_g_, so that the rounded end of glass is exposed.
8. Complete the assembly of the aspirator by placing the rubber stopper
snugly into the vial. The vial aspirator is now ready for use.
If a piece of glass tubing 1¼ inches in diameter and 8 inches long is
available, then a tube aspirator can be made, fig. 5. In making a tube
aspirator, use two one-hole rubber stoppers, 5_b_. Cut the pieces of
glass tubing as shown in fig. 5_c_, 5_e_, and 5_g_. Using a piece of
rubber tubing, 5_f_, complete the minor details as described for the
vial aspirator, not forgetting the cheesecloth, 5_e_, and assemble the
parts as shown in fig. 5.
Use and Care.—To catch an insect with the aspirator shown in fig. 4 or
fig. 5, put end piece, _g_, in your mouth, grasp the vial or tube, _a_,
in your dexterous hand, aim the intake tube, _c_, at the insect and
almost touching it; suck suddenly and hard. The air current pulls the
insect in; the insect usually does not find its way into the intake tube
to crawl out. The cheesecloth, _e_, prevents the insect from being
sucked into your mouth.
To kill insects in the aspirator, use a small cyanide bottle, 4_i_,
which is inserted in a cork, 4_h_, that has been partially bored through
to receive it. This cork should be the exact size of the vial or tube
for which it is intended.
[Illustration: Fig. 6.—Sifter with hand grips. Debris containing
insects is sifted over a piece of white oilcloth. The sifter, not
more than half full, is shaken gently at first and then violently.
Finally the debris that cannot be shaken through the sifter is
emptied on the oilcloth, and specimens too large to go through the
mesh of the sifter are captured. Patience is required to get the
best results with the sifter, which provides one of the best methods
for winter collecting.]
To use the cyanide cork with the vial aspirator shown in fig. 4, simply
exchange the corks. If the glass tube aspirator is used, plug the intake
tube, 5_c_, with a tapered paper plug or a leaf, jar the insects away
from the stopper at the opposite end, remove this stopper cautiously,
and quickly insert in its place the cyanide cork. When the specimens are
stupefied, they may be transferred to another bottle.
The cyanide corks are highly poisonous. Between times of use with an
aspirator, keep each of these corks inserted tightly in a bottle or vial
labeled “POISON,” as in fig. 3.
Sifter
Perhaps no special collecting method results in more interesting, rare,
and diverse kinds of insects than that involved in sifting rotten logs,
leaf mold, and other forest and prairie ground cover. To do this type of
collecting, provide yourself with the following:
1. A stout sifting sieve about 12 by 12 inches and 4 to 6 inches deep,
fig. 6. The bottom may be wire screen of any desired mesh; usually 8,
10, or 12 meshes to the inch give good results.
2. A sturdy piece of white oilcloth about 18 inches or 2 feet square.
3. Collecting equipment, including an aspirator, camel’s-hair brush,
forceps, vials, and killing bottle.
Material such as leaf mold is placed in the sieve and this is shaken
over the white oilcloth, which has been spread on a level spot on the
ground. The small insects fall on the cloth and can be picked up with
the aspirator or the camel’s-hair brush. Many insects feign death when
they fall to the oilcloth and they are difficult to detect in the bits
of sifted material until they “revive” and start to move.
In late fall and winter, sifting provides one of the most profitable
types of collecting; in any season, it will turn up such things as rare
spiders and beetles. Sifting is most successful for finding large,
active insects. For small, slow-moving forms, Berlese funnels offer a
better collecting method.
Berlese Funnel
When you are wandering through woods or fields, do you realize that you
are stepping on more insects than you ever see? The ground cover and
soil are inhabited by a vast assemblage of little animals that are
seldom seen by the casual collector. Because many of these animals are
exceedingly minute, they are difficult to see and collect by ordinary
methods.
Construction.—The most efficient method for collecting this fauna is by
the use of Berlese funnels, named after the Italian entomologist Berlese
(pronounced Bur-lazy), who first used them extensively. A Berlese funnel
is a very simple apparatus, consisting of a fairly long funnel,
suspended wide end up, with, a screen placed about a third of the way
down the funnel; heat is applied either around the upper portion or over
the top of the funnel, and a container of preservative, preferably 80
per cent ethyl alcohol, is placed at the small bottom opening. Leaf mold
or other material is placed on the screen, the heat source is turned on,
and soon the animals begin to leave the drying sample and migrate
downward, dropping into the preservative.
[Illustration: Fig. 7.—Diagrammatic cross section of a Berlese
funnel. The central figure shows an arrangement for a steam coil,
the lower left for an electric light.]
Fig. 7 illustrates a funnel that has proved very satisfactory; it is 15
inches from top to bottom, and the top has a diameter of 12 inches. The
bottom opening, seven-eighths inch in diameter, fits into the mouth of
the bottle containing the preservative. Three angled brackets or hangers
are soldered inside the funnel to provide a rest for the screen, which
is made of quarter-inch or eighth-inch mesh hardware cloth; the mesh
used depends upon the type of sample. A battery of several funnels in a
rack, fig. 8, will allow the collector to sample several kinds of
material at the same time.
If steam is used as a source of heat, the small copper lines that
conduct it act as a partial support for the funnel by encircling it
about halfway between the screen and the top; a piece of cloth is tied
tightly over the top of the funnel to prevent the upward escape of
animals. If an electric light is used for heating, it should be hung
directly over the center of the funnel, no cloth should be tied over the
top, and the light should have a reflector nearly as wide as the top of
the funnel.
[Illustration: Fig. 8.—Berlese funnel in position on rack. Each
funnel rests inside a double ring of copper tubing (visible at
extreme lower left), through which live steam flows. The steam
produces heat that dries out the sample of leaf mold in the funnel
and drives animals into a bottle of preservative below. Cotton or a
small rag is tamped between the end of the funnel and the mouth of
the bottle to prevent escape of specimens.]
Care must be taken not to heat the sample too rapidly. Otherwise, either
moisture will condense in the lower part of the funnel and trap many of
the animals working their way toward the bottom, or the heat will kill
many of the organisms before they have an opportunity to move out of the
sample. An application of heat sufficient to dry the sample in 4 or 5
days is usually satisfactory.
The Berlese funnel is extremely useful for collecting many groups of
beetles (particularly Staphylinidae), thrips, springtails, many groups
of parasitic Hymenoptera, ants, mites, pseudoscorpions, millipedes,
centipedes, and a wide range of other minute animals that live in soil,
surface cover, logs, or bark.
Collecting Berlese Samples.—Many different habitats and micro-habitats
provide good samples for the Berlese funnel. You will find that, for
general collecting, various types of ground cover are excellent; for
leaf mold samples, scrape off and discard the dry surface leaves and
scoop up the lower, rotted layers of leaves together with an inch or two
of the adjacent soil. You may encounter especially good samples where
leaves have blown in along the edge of a log. In such a situation, take
some of the log bark with the sample. Collect rotten log samples in
large hunks and break them up just before putting them in the funnel.
From either standing stumps or fallen logs in which the wood is still
too hard to break up, collect the loose bark, as it is often quite
productive. Frequently, if you roll a log over, you may find animal runs
under it; the debris and earth under and around these runs, together
with animal nests, frequently give unusual catches, such as larvae and
adults of fleas and rare ticks. Especially productive are samples taken
from the interior of a standing hollow tree; from the bottom of the
hollow you can scoop out a foot or more of fine, rotten, woody material
rich in rare insects.
Certain items placed in the funnel may produce distinctive and unusual
catches. Recently deserted birds’ nests will give mites and, frequently,
rare beetles, flies, and their larvae; mature or overmature mushrooms
and bracket fungi are often rich in beetles, thrips, and maggots; bark
of living trees may produce unusual thrips, springtails, and psocids;
debris from aquatic habitats and from the wet edges of ponds and tiny
streams may be productive of rare aquatic and semiaquatic forms. Moss is
a good source of peculiar species of springtails, thrips, and beetles;
the moss should be rolled up carefully while being transported.
Handling Berlese Collections.—In the field, put samples of leaf mold or
other material in tightly woven cloth bags or strong paper bags for
transportation. It is convenient to have small paper bags for mushrooms,
nests, and other small items, and larger bags for ground cover, moss,
and the like. When collecting ground cover and similar material, put in
each bag enough of a sample so that it will not shake around loosely,
but do not pack it tightly. Be sure that samples do not overheat while
being transported.
Samples may be collected at any season. If collected during warm
weather, they should be taken to a laboratory and placed in the funnels
within a day or two; otherwise, considerable loss of population occurs
within the samples. If collected during cold weather, they may be kept
in cold storage for a week or two with little loss of fauna.
In putting material in the funnel, lay it carefully on the screen to a
depth of a few inches. Moss and sod should be placed upside down in a
single layer on the screen. In the case of dense material, pile the
sample chiefly around the sides of the funnel and leave an opening in
the middle, as shown in fig. 7. After the funnel is loaded, place it in
the rack, put the bottle of preservative under it, and apply the heat.
By substituting a different kind of collecting bottle at the bottom of
the funnel, you may obtain live material for rearing. The exact changes
necessary to obtain live material will depend upon your ingenuity and
the type of material you desire.
Equipment for Collecting Aquatic Insects
Hundreds of different kinds of insects are aquatic and offer rich
collecting possibilities. In all instances, the immature stage lives in
water, but in most of them the adult stage emerges on land or flies in
the air. For this reason several types of collecting are needed to
obtain a good sampling of aquatic insects.
Night Collecting of Adult Insects.—Collecting at lights on warm, cloudy
nights, or warm nights without moonlight, gives best results. Two simple
methods are as follows:
Drive your car to a spot overlooking a stream or lake and turn on the
bright lights. Into a shallow pan, such as a pie pan, pour enough
alcohol to cover the bottom with one-eighth to one-fourth inch of fluid.
Hold the pan directly under a headlight. If aquatic insects are on the
wing, they will come to the light and eventually drop in the fluid,
which traps them. With a small piece of wet cardboard, you can scrape
the entire insect contents of the pan into a small bottle of alcohol,
which you should then label, giving date, name of collector, and
location.
Lights in signs and store windows (especially blue neon signs) near
fresh water attract large numbers of aquatic insects. You may capture an
insect easily by dipping an index finger in a bottle of alcohol,
“scooping up” the insect rapidly on the wet surface, and then dipping it
in the bottle. An aspirator also can be used with success.
Day Collecting of Adult Insects.—During the day, aquatic insects
frequently rest on or under bridges, window ledges, and similar places,
and show a preference for dense trees in shaded situations. They are
especially numerous in those spots where the heavily leaved branches
hang low over the water and form humid, protected areas in the heat of
the day. Here sweeping with a stout and fairly wide-mouthed net is very
effective. Aquatic insects may often be picked off stones in such
places, especially early in the season.
Collecting Larvae.—Practically every stream or lake has some aquatic
insect larvae which may be collected by various methods, some simple and
others requiring specialized and complicated apparatus. For general
collecting, the following suggestions may be of value:
1. Look under logs and stones. Search out crevices in them; some insects
hide away and demand of the collector a keen and careful search.
2. Tear apart bunches of leaves, roots, and other debris that may have
piled up in front of a rock or log, or that may have accumulated at the
end of a root or branch dangling in the water.
3. Pick out bunches of aquatic plants and search through them carefully.
4. Sift mud, sand, or gravel taken from the bottom of a lake or stream.
Remember that some insects build cases in which they hide when
disturbed. It takes a practiced eye to see a motionless case. After an
insect has dried out a little, it partially emerges from the case and
drags it along in search of water; moving in this way, it is easy to
see.
HOW TO HANDLE UNMOUNTED SPECIMENS
Soon after insects are killed they dry out, become very brittle, and are
damaged easily. Small, fragile insects especially are susceptible to
breakage and, when dry, break up readily into fragments. Hard-shelled
insects, such as beetles, may appear to be sufficiently durable to
withstand handling when dry, but even these insects have fragile legs,
antennae, and other parts which snap off readily when handled dry. Newly
killed material should be either mounted or put in temporary storage
before it has dried out. If collected material dries out before it can
be mounted or stored, it should be relaxed by special techniques so that
the specimens can again be handled without danger of breakage.
Temporary Cases
If it is not convenient to mount the specimens when they are taken from
the killing bottle, the moths and butterflies should be put in _papers_
and other insects in cellucotton.
Papers are simply rectangular strips of paper of convenient size folded
as in fig. 9. A moth or butterfly, with its wings folded, is placed in a
paper, the edges of which are then crimped over to lock it shut.
For insects other than moths or butterflies, cardboard pillboxes
containing cellucotton make good temporary housing, fig. 10. A layer of
cellucotton is laid in the bottom, a layer of insects placed on it, and
another layer of cellucotton placed over the insects. The lid should fit
fairly snugly over all. Cigar boxes and other boxes of like size also
may be used in the same way.
[Illustration: Fig. 9.—Papers. These are temporary means of keeping
dragonflies, moths, butterflies, and small insects of other kinds
until they can be relaxed and mounted. A rectangular piece of paper,
of a size suited to the insect it is to contain, is folded along the
dotted lines and in the directions indicated by arrows, as shown in
_a_, _b_, and _c_.]
Great care must be taken that sufficient cellucotton is put in the box
to take up all moisture in the insect bodies. If the specimens are
large, they should be allowed to dry moderately uncovered before being
placed in cellucotton in storage containers. If insects become damp in
the containers they quickly mold or rot. The containers should be wood
or cardboard boxes, for they will not sweat, as will a metal box. The
insects should be packed tightly enough to prevent their rolling around
and breaking.
Relaxing Boxes and Jars
At any desired time the dry specimens may be relaxed and mounted. A
relaxing box or jar is easily made. In the bottom of a wide-mouthed jar
with a screw-on lid, put an inch or two of clean sand; saturate the sand
with water containing a small amount of phenol (carbolic acid) and place
over it a piece of cork, cardboard, or wood cut to fit the jar. Place
the dry specimens on the cork or other material, and cover the jar
tightly with the screw-on lid. The lid must be practically airtight. In
a day or two the specimens will be soft and pliable enough for pinning
or spreading, the next steps toward permanent arrangement of the
collection.
[Illustration: Fig. 10.—Pillbox for temporary storage of insects.
Enough cotton packing is placed in the box to keep the specimen from
rattling about but not so much that it crushes the specimen.]
The relaxer will sweat if kept in too hot a room and will spoil the
specimens. Also, the insects will be spoiled if left in the relaxer too
long. The correct length of time varies with each relaxer and can be
learned only by experience.
HOW TO MOUNT AND PRESERVE SPECIMENS
Most adult insects in collections are mounted on pins. Most medium-sized
to large insects, such as grasshoppers, butterflies, moths, flies, bees,
and many beetles should be pinned directly through the body from top to
bottom. Many small insects, such as leafhoppers, plant bugs, small
beetles, and the like, should be glued on card points. Immature insects
and the adults of some groups are best preserved in fluid.
Preservation by Pinning
Hard-bodied insects, such as beetles, flies, and wasps, are preserved as
dry specimens on pins better than in fluid. The pinned specimens are
more convenient to study and they retain their natural coloring better.
Flies and butterflies are covered with hairs or scales that clot or
break off if the specimens are preserved in fluid, and for this reason
they should be pinned.
[Illustration: Fig. 11.—Pinning. Medium- to hard-shelled insects are
mounted by being pinned through the body in the manner shown at _a_.
The black spots show the location of the pin in the case of bees,
flies, and wasps, _b_; stink bugs, _c_; grasshoppers, _d_; and
beetles, _e_.]
Common household pins are too thick and short for pinning insects.
Longer, slender pins called insect pins are necessary and may be
purchased from various supply houses. They should be of spring steel; a
brass pin will corrode and be destroyed by acids in the insect’s body.
The pins are available in numbered sizes, of which 1, 2, 3, and 4 will
be found of most general use, and sizes 0 and 00 of advantage in special
cases.
Medium to Large Insects.—Medium to large hard-shelled insects such as
moths, beetles, flies, bees, and wasps, should be pinned vertically
through the body, fig. 11_a_. It is essential that the pin pass through
a fairly solid part of the body, and, to insure this, the following
standard procedures should be adopted:
1. Bees, wasps, flies.—Pin through thorax between bases of front wings
slightly to right of middle line, fig. 11_b_.
2. Stink bugs.—Pin just to right of middle line of the scutellum or
large triangle between the bases of the front wings, fig. 11_c_.
3. Grasshoppers.—Pin through back part of prothorax (the saddle behind
the head) just to right of middle line, fig. 11_d_.
[Illustration: Fig. 12.—Pinning. Moths, _a_, and butterflies, _b_,
are pinned through the center of the thorax (instead of to the right
of the median line) between the bases of the front wings.]
[Illustration: Fig. 13.—Pinning block. The block is 1¼ × 1¼ × 2¼
inches, with holes drilled to the depths shown and having diameters
only slightly greater than the largest pin that will be used. A
specimen is pinned and the pin inserted into one of the holes until
the pin touches bottom; thus, insects may be pinned uniformly at a
desired height.]
4. Beetles.—Pin near front margin of right wing cover near middle line,
fig. 11_e_.
5. Moths, butterflies, dragonflies, damselflies.—Pin through the center
of the thorax between the bases of the front wings, fig. 12.
The insect should be pushed about three-quarters of the distance up the
pin, but not so close to the top that no room is left for easy handling
of the pin with the fingers. It is well to have all insects the same
distance from the top of the pin. To insure a uniform distance, the
collector should use a pinning block. This is a small piece of wood or
metal usually in the form shown in fig. 13, into the top of which are
drilled holes slightly larger than the pin diameters. Such a block may
be fashioned of wood with holes made by small nails and covered with a
cardboard rectangle through which have been stabbed holes the exact size
of those in the wood. The depths of the holes in the block should be
three-eighths inch, three-quarters inch, and 1⅛ inches, respectively. To
use the block, pin the insect and insert the pin into whichever hole
allows the specimen to be pushed up the pin and still leave room,
allowing for the thickness of the insect’s body, for handling at the
top.
[Illustration: Fig. 14.—Pinning small insects and labeling. The
insect may be glued to a card point, _a_, which has been crimped to
meet the right side of the body, _b_, _c_; or it may be pinned with
a minuten pin, _d_, to a piece of cork or pith, which in turn is
regularly pinned. All pinned insects should be labeled, as at _e_.
In the case of some small insects, such as tiny moths, the minuten
pin may be run down through the body and then into the cork; in the
case of others, such as mosquitoes, it is often desirable to run the
minuten pin up through the cork first and then impale the specimen
on the point of the pin.]
Tiny Insects.—Very small insects should be mounted on card points or on
minuten pins. Regular pins would break too many of the insects’ body
parts.
Card points are small triangles of cardboard or plastic pinned through
one of the sides and crimped over at the opposite apex; a spot of strong
glue is put on the angled tip, and the right side of the insect is
pressed against the glued surface, fig. 14. The slant of the crimp
depends on the angle of the insect’s side; the desired product is the
insect mounted with its top surface horizontal and its head forward;
legs, wings, and antennae should be in view and as little of the body as
possible hidden by the glue or card point. Very little glue should be
used; a small amount holds well and gives a better specimen for study
than a large amount. The points may be cut uniformly with a hand punch,
and they should be about three-eighths inch long. Good material for
making these points is 2-ply Bristol board.
[Illustration: Fig. 15.—Pinning crane flies. Because of their
unwieldy legs, these insects should have a double card point mount,
and the legs should be kept away from the pin so that they will not
be broken in handling.]
Minuten pins are short, extremely delicate steel pins, fig. 14_d_. One
of these is thrust through the body of the insect and into a small piece
of cork, pith, or similar substance, which is in turn pinned in the
regular way a card point is. This method is especially desirable for
tiny moths.
Insects Hard to Pin.—Wasps, lacewings, damselflies, and similar insects
have an abdomen that sags readily when the specimen is killed and
pinned. This unwanted drooping can be prevented in three simple ways.
(1) Stick the pinned insect on a vertical surface of a block so that the
body by its own weight dries in normal position. (2) Pin the insect on a
horizontal surface and run a stiff paper on the pin beneath the body in
such a way as to support it in a natural position until the insect
dries. (3) Brace the abdomen by crossing two pins beneath it and
thrusting them into the block, allowing the specimen to dry in the angle
of the cross.
Crane flies are unwieldy and so are best pinned on a double card point
mount, fig. 15. The legs should be directed away from the pin to avoid
breakage in handling.
Spreading Board for Moths and Butterflies
Moths and butterflies should have their wings spread before being put
into the collection. To do this well, it is necessary to have spreading
boards that are accurately made but that are not necessarily complicated
or expensive.
Construction.—A convenient board for medium-sized insects can be made at
home of the following materials:
1.—A hardwood base, 4 × 12 × ¼ inch.
2.—Two hardwood end pieces, 4 × ¾ × ½ inch.
3.—Two softwood top pieces, 1⅞ × 12 × ½ inch, with the top surface
planed at an angle, so that the thickness at one edge is ½
inch and at the other ⅜ inch.
4.—Two flat cork pieces 1 × 11 × ³/₁₆ inch.
Nail the top pieces to the ends so that the slanting surfaces of the
tops are uppermost and the narrower edges parallel and one-quarter inch
apart, fig. 16. Glue one strip of cork beneath the top pieces, covering
the opening between and fitting snugly at each end. Glue the other cork
piece flat to the upper side of the base, lengthwise along the middle,
and extending to within one-half inch of each end. Finally, nail the
base across the bottoms of the end pieces, so that the two corks face
each other.
Use.—Before spreading the specimen, relax it as described under
“Relaxing Boxes and Jars.” Then pin it, keeping in mind fig. 12 and the
directions given under “Preservation by Pinning.” Thrust the pin, with
the insect on it, through the upper cork of the board and into the cork
on the base. Insert the insect body in the groove so that the wing bases
are level with the near edge of each top piece. Hold the wings at the
top level by two narrow strips of paper and pull them forward until the
hind margin of the front wing is at right angles to the body axis, and
the front margin of the hind wing is just under the front wing, fig. 16.
Pin the wings temporarily in this position by inserting a pin, size 0 or
00, near the front margin at the base of each wing. When the wings on
both sides of the insect are thus adjusted, lay strong pieces of paper
over them and pin them down securely with large pins inserted close to
the wings but not through them. Here you may use large common pins, but
still better are the large-headed dressmaker’s pins about 1¼ inches
long. Finally, remove the original adjusting pins and put the specimen
in a dry, pest-proof container for 2 or 3 weeks. It will then have set
sufficiently to be removed from the board.
[Illustration: Fig. 16.—Spreading board for moths and butterflies.
The insect is pinned with its body in the groove and, temporarily,
with all its wings drawn forward and pinned as shown for the right
wings. Then all wings are pinned as shown for the left wings, and
the insect is allowed to dry. The inset shows a view of spreading
board construction. The top pieces of the board must be smooth and
of soft wood. First grade pine is satisfactory.]
For good results, spreading boards with grooves of various widths are
necessary; a specimen should be spread on a board with a groove that
fits the body. The width of the top pieces should vary to accommodate
different wingspreads. The slope of the top pieces should be about as
described.
Preservation in Fluid
Caterpillars and other immature stages of insects should be preserved in
80 per cent grain alcohol. Caterpillars, grubs, and maggots should first
be heated 5 to 10 minutes in water just at the boiling point. This
treatment sterilizes the specimens and prevents their discoloration by
bacteria in the digestive system.
Many soft-bodied adult insects, including bristletails, springtails,
stoneflies, and caddisflies, also should be preserved in fluid. If
pinned, they shrivel to such an extent that few identifying characters
can be seen. The preserving fluid in the vials in which insects have
been placed should be changed at the end of the first day or two.
Some hard-shelled insects may be preserved in fluid. Ants and beetles
may be thus treated temporarily and later pinned and dried.
HOW TO LABEL THE SPECIMENS
To be useful to the entomologist and others interested in the scientific
relations of insects, as well as to furnish the collector with a
complete record of his hours in the field and make more valuable the
work he has already accomplished, the specimens should be labeled. The
important information to be put on the label of each specimen is the
locality and date of capture, but greater scientific value will be
attached to the specimen by adding the name of the collector and the
host on which the insect was found, or the particular habitat in which
the insect was caught.
Labels should be made of a good grade of white paper stiff enough to
stay flat when pierced and pushed up the pins. A very satisfactory high
quality paper is available under the name “substance 36 ledger.” The
labels may be printed by hand with a crow-quill pen and black India ink,
or they may be purchased completely or partially printed from a
biological supply house. They should be as small as possible and of
nearly uniform size. They should be pushed up the pins, fig. 14, not too
near the specimens, and they should project from the pins in the same
direction as the specimens. To keep the labels small, yet to include all
desirable information, it is often well to record the locality,
collection date, and collector on one label, and the host plant or other
pertinent information on a second label, fig. 14.
When the specimen is identified, its name should be recorded on still
another label, which should be kept low on the pin. Sample
identification labels are illustrated by the bottom labels in fig. 14.
HOUSING THE COLLECTION PERMANENTLY
After the specimens have been pinned and labeled, they should be housed
in boxes or cases having a soft bottom or inner layer that will allow
easy pinning. Such housing not only insures the safety of the collection
but makes for easily handled units once the specimens have been named.
Insect Boxes
Several satisfactory types of boxes for housing insect specimens may be
bought from commercial supply companies. These are usually much better
than boxes of home construction, being more nearly dustproof and
pestproof. Homemade boxes, however, are quite practical for the
beginning collector, due to their ease of construction and extremely low
cost. Cigar boxes 2 inches deep or more make ideal insect boxes if a
layer of cork or balsa wood or two layers of soft, corrugated cardboard
are glued in the bottom. Other wooden or cardboard boxes may be provided
with such a bottom pinning surface and used for storing specimens. Boxes
of this type, however, afford the specimens no protection against pests,
and great care must be exercised in keeping the boxes fumigated.
Manufactured boxes, cabinets, and cases may be selected from catalogs
that various scientific supply firms send free upon application.
Precaution Against Pests
Certain insects, such as flour beetles and carpet beetles, feed upon
dried insects, and unless precautions are taken these may entirely
destroy a collection. To guard against them, various chemical repellents
may be placed in the boxes containing specimens. Naphthalene, of which
ordinary mothballs are composed, is one of the best repellents. A few
mothballs may be put in a cloth bag pinned securely in one corner of the
box, or the heads of common pins may be inserted into naphthalene
mothballs, and the points stuck in the corners of the box, fig. 17.
Naphthalene is chiefly repellent in action; its odor keeps out pests,
but, if they are already in the specimen boxes, naphthalene will usually
not kill these pests, and some other substance must be used.
Paradichlorobenzene, called PDB, is a good fumigant to use on pests in
the collection. It should be used in a nearly airtight container, such
as a tight trunk, bin, or case, at the rate of 1 pound of PDB to 25
cubic feet of space. The boxes of specimens, with lids open or removed,
should be placed in the container, the fumigant scattered or spread on a
piece of cloth or paper above them, and the container sealed for about a
week.
[Illustration: Fig. 17.—A naphthalene mothball mounted on a common
pin. It serves as a repellent to keep away from the collection live
insects that might cause damage. To insert the pin, stick the point
in a cork, heat the head in a flame, and then push the head into a
mothball. The pin will melt its way into the naphthalene, which will
cool and harden again almost immediately.]
THE INSECT WORLD
When the insects have been collected, mounted or preserved, and labeled,
the next step is to identify or name them. This is no easy task, because
there are so many different kinds of insects. In the whole world there
are well over 1 million different kinds and in Illinois alone probably
20,000 different kinds.
The identification of insects is simplified somewhat by the fact that
many species are closely related and can be classified into a number of
major groups. Insects as a whole constitute what is called a _class_ of
animals, the Insecta. The crabs, shrimps, and their allies constitute a
class called the Crustacea; the snakes, turtles, lizards, and their
allies constitute another class called the Reptilia; and so on. The
entire insect class is divided into _orders_, such as the Coleoptera, or
beetles, the Diptera, or flies, and the Siphonaptera, or fleas. Each of
these orders may contain several dozen to 25,000 different kinds of
insects in North America alone. These orders are divided into
_families_, each of which may contain one species to many thousands of
species. The family names always end in _-idae_, as in Pentatomidae, the
name for the stink bugs. The families are divided into _genera_ (the
plural for genus), and the various _species_ (the word is the same for
both singular and plural) or kinds are placed in the genera.
The house fly bears the name _Musca domestica_ Linnaeus; this means that
the species name is _domestica_, that the name was first applied to the
species by Carolus Linnaeus (known as the describer of the insect or the
author of the name), and that the species _domestica_ is in the genus
_Musca_. The genus _Musca_ belongs to the family Muscidae, which, in
turn, belongs to the order Diptera of the class Insecta.
Scientists may decide that a certain species belongs in another genus.
When the species is transferred from the genus in which it was
originally described to another genus, the name of the author is placed
in parentheses. For example, the chinch bug was originally described by
Thomas Say in the genus _Lygaeus_ and had the name _Lygaeus leucopterus_
Say. Later the species _leucopterus_ was transferred to the genus
_Blissus_, and Say’s name was placed in parentheses, thus: _Blissus
leucopterus_ (Say).
In the process of growth, insects go through a series of interesting
stages. When the immature insect reaches a certain size, its outside
skin covering or cuticle will not stretch further and the insect then
acquires a larger cuticle by a process called _molting_.
Molting consists of a definite sequence of steps: (1) A goodly portion
of the inside layer of the cuticle is dissolved by special glands
situated among cells immediately below the cuticle; (2) the cells under
the cuticle then exude material which forms a new cuticle beneath what
is left of the old cuticle; (3) when the new cuticle is completely
formed, the insect breaks a slit in the old cuticle, crawls out of it,
and leaves it behind in the form of a cast skin; (4) the insect goes
through many contortions, during which the soft parts of the new cuticle
are stretched to a larger size than the corresponding parts of the old
one; (5) the cuticle becomes set and unstretchable almost immediately,
and the insect resumes its normal activities. During the molting
process, the hard plates of each new cuticle are formed a size larger
than the corresponding parts of the old cuticle, and the soft parts are
stretched a size larger than the old. When the insect resumes its normal
activities immediately after a molt, the soft parts of the cuticle fall
into a large number of pleats or folds between the hard parts. As the
insect grows larger following a molt, the body can lengthen by the
unfolding of these pleated areas.
The stages of the insect between molts are called _instars_. Among the
different orders of insects the number of instars in the life history
may vary, and various instars may have different forms. These
characteristics of molting and instars are therefore important items in
the classification of insects.
[Illustration: Fig. 18.—A family tree representing current ideas of
how the orders of insects evolved. The early, primitive orders are
at the bottom of the tree and the later, more highly specialized
orders at the top. It is customary to list the orders of insects in
this sequence, from primitive to specialized.]
_Larvae and pupae evolved_
MOTHS, BUTTERFLIES
FLIES
ANTS, BEES, WASPS
BEETLES
CADDISFLIES
LACEWINGS
FLEAS
SCORPIONFLIES
ALDERFLIES
_Wing folding evolved_
BUGS
GRASSHOPPERS
THRIPS
EARWIGS
LICE
TERMITES
BARKLICE
MANTIDS
COCKROACHES
ZORAPTERANS
STONEFLIES
_Wings evolved_
DRAGONFLIES
MAYFLIES
_Primitive wingless insects_
SPRINGTAILS
PROTURANS
SILVERFISH
CAMPODEIDS
BRISTLETAILS
The insect orders are arranged in a classification based on the sequence
in which the orders are believed to have evolved, fig. 18. Measured by
geological time, insects are among the oldest of land animals, having
first evolved from an earlier, centipede-like ancestor about 400 million
years ago. The first insects had no wings and differed from the
many-legged centipede-like creatures of that time chiefly in having only
three pairs of functional legs. The legs were situated on the three
segments immediately behind the head; the three distinctive segments are
together called the _thorax_. The part of the body behind the thorax is
called the _abdomen_. In contrast to this arrangement, a centipede has a
pair of legs on each of its many segments for the whole length of the
body. The slow evolutionary change from such a many-legged ancestral
form to a typical insect undoubtedly occurred by a gradual enlargement
and strengthening of the front three pairs of legs and a reduction of
the legs posterior to these. Evidence supporting this idea is found in
insect embryos, which normally have rudimentary leg structures on the
abdominal segments, and in some of the extremely primitive insects,
which have rudimentary legs called styli on some segments of the
abdomen. The result of this evolutionary development is a body having
the front part, the thorax, specialized for locomotion and the back
part, the abdomen, serving chiefly as a container for the vital organs,
such as those of the digestive and reproductive systems.
[Illustration: Fig. 19.—Diagram of a typical adult winged insect.
This illustrates many of the parts that are useful in identifying
these creatures. (Drawing adapted from R. E. Snodgrass.)]
HEAD
Antenna
Ocelli
Eye
THORAX
1
Front leg
2
Front wing
Middle leg
3
Hind wing
Hind leg
ABDOMEN
Cercus
Five existing orders of insects, all found in Illinois, are
representative of the primeval wingless insects. In all five, the
individual molts at intervals, even after becoming adult and sexually
mature, and the old and young are extremely similar. Three of the
primitive orders, the campodeids, proturans, and springtails, belong to
a specialized early branch of the insect family tree, fig. 18, in which
the cheeks have grown forward to form a pouch surrounding the
mouthparts. In the other two primitive orders, the bristletails and
silverfish, the mouthparts are in a normally exposed condition, but the
legs are larger and the insects are rapid runners.
From one of these ancestral, silverfish-like insects arose a form in
which wings evolved. In birds and bats, the wings are converted front
legs with membranes or feathers attached to form planing or flying
surfaces. In insects, on the other hand, the wings are outgrowths of the
edge of the body where the sides and top come together, fig. 19. The
wings probably began as side flanges of the thorax and permitted a
certain amount of planing. Whatever their origin, two pairs of flying
wings did evolve, one pair on the second and another on the third
segment of the thorax.
In the early winged forms, the wings could not be folded back in repose
over the body, but were held out from the sides like airplane wings or
together above the body like sails. Two living orders of insects
represent this type, the mayflies and the dragonflies. In both of these,
as in other winged insects, the wings form as small pads during the
early stages of the individual; then at a final molt they are unfolded
as functional units. In the mayflies, one more molt occurs after the
wings are formed; in this molt the old outside covering of the wings is
shed along with that of the rest of the insect. In all other winged
insects no molt occurs after the wings are formed and the individual
becomes sexually mature.
Insects having erect, nonfolding wings were abundant some 300 million
years ago. Fossil remains of many of these early forms have been found
in the Mazon Creek area in Illinois, fig. 20.
From one of these early winged types a form evolved in which the wings
could be folded compactly over the body; this form gave rise to a great
many of our present-day insects. In the first insects that evolved from
this form the wing pads of the immature stages, called nymphs, grew as
external and often inconspicuous flaps held close to the body. These
primitive insects comprise three distinctive groups, characterized
mainly by differences in leg and body structure. One group contains the
cockroaches, grasshoppers, and their allies; the second includes only
the stoneflies; and the third group includes the barklice, true lice,
bugs, and their allies.
[Illustration: Fig. 20.—An insect fossil from an iron nodule or
concretion found at Mazon Creek, Illinois; hind leg of an ancestral
mayfly, _Lithoneura mirifica_ Carpenter. Actual length of wing about
one-half inch. This fossil represents an insect which lived during
the Pennsylvanian period, about 250 million years ago. (Photograph
courtesy of Illinois State Museum.)]
One of the primitive lines of wing-folding insects, possibly an offshoot
from the base of the barklouse-bug line, evolved into a distinctly
different type in which the wing pads of the immature stages developed
internally and appeared as external pads only in the stage before the
adult form. The type was characterized by a marked difference of
appearance between the various stages of the life history; these stages
have been given distinctive names. The first immature stage, which is
without external wing pads, is called a _larva_; the single stage with
the external wing pads is called the _pupa_; and the final winged,
sexually mature stage is called the _adult_. The larva is essentially a
growing stage, the pupa is a quiescent stage of internal reorganization,
and the adult is the _egg_-producing stage. This type of insect
gradually gave rise to the orders which now contain the largest number
of species, including the beetles, moths, and flies. In many lines of
this neuropteroid branch, as it is called, the larva has become adapted
to a mode of life quite different from that of the adult. Many fly
larvae, for example, live in rotting organic material or live as
parasites within the tissues of other kinds of insects, whereas the
adult flies often feed at flowers on pollen and nectar, visiting the
site of the larval habitat only to lay eggs. As a result of this type of
evolution, members of the neuropteroid orders exhibit many bizarre and
complicated life histories.
Occasionally certain groups of winged insects evolved new types which
had small wings or were wingless. The new types resulted because the
groups were subjected to environmental situations where wings were of
little survival value. Within the groups, individuals with smaller wings
were favored; they survived and reproduced in greater numbers than other
individuals. Over many generations then, the wings in some groups became
very small or were entirely lost. Sometimes this loss of wings occurred
in all the adult forms, as in the fleas. Individuals of only one sex may
be wingless, as are the females of two Illinois moths, one of which
produces bagworms and the other cankerworms. In two groups, the termites
and the ants, a wingless worker or soldier caste is produced; in these
groups the normal adults which swarm and reproduce are fully winged.
These winged forms establish new colonies.
Wings were lost in the evolutionary development of two insect groups
that became parasites of warm-blooded animals, both birds and mammals.
Each of these insect groups developed into a large, distinctive order.
One order, the true lice, evolved from the barklice, and the other, the
fleas, evolved possibly from a primeval fly group. Although these two
orders, the lice and the fleas, are without wings, the structure of
their bodies and their life histories provide adequate testimony of
their evolutionary affinities.
The following synopsis of Illinois insects treats the various kinds in
the sequence in which we believe they evolved, from the extremely
primitive bristletails to the highly specialized flies.
HOW TO IDENTIFY SPECIMENS
As an aid to the beginner in making preliminary identification of his
specimens and also as an aid in arranging his collection, a short
descriptive synopsis of the orders of living insects is given below. In
this description are noted the most distinctive features of the common
insects occurring in Illinois. There are rare and obscure forms, seldom
met by the collector, that require a more technical key for their
identification; for these the collector will need to consult some of the
more nearly complete books listed on page 70. The collector will find,
however, that this synopsis will afford a beginning for his
classification of the common forms.
Various characters are used to identify an insect to family, genus, and
species. Among these characters are the antennae, wings (if present),
legs, and mouthparts. Frequently important for identification are such
minute details as hair or scales covering the body or wings and the
texture of these parts. In most cases good microscopic equipment is
necessary to see clearly the characters used in the diagnosis of
insects.
SYNOPSIS OF ILLINOIS INSECT ORDERS
Of the 28 orders of insects recognized in North America, 26 have been
collected in Illinois. The two orders not found here are the Embioptera
or webspinners, a tropical and subtropical order, and the Raphidiodea or
snakeflies, which occur in the western mountainous region of the
continent.
The Illinois fauna thus contains a remarkable variety of insects,
including forms such as the bristletails, mayflies, and cockroaches,
which are practically “living fossils” of insects that lived hundreds of
millions of years ago.
Primitive Wingless Insects
Only five orders of primitive wingless insects are known; species of
each order occur in Illinois. These orders represent the stages in
insect evolution before wings had appeared.
[Illustration: Fig. 21.—Diplura. A campodeid belonging to the genus
_Campodea_, found under stones in moist places. Actual length of
adult about 0.1 inch. (Drawing from E. O. Essig.)]
[Illustration: Fig. 22.—Protura. _Acerentulus barberi_, a proturan
found on sticks and leaves in the leaf mold of forests. Actual
length of adult about 0.02 inch. (Drawing from H. E. Ewing.)]
Diplura
Campodeids, Japygids
Small, wingless, fragile, blind, whitish insects that run fairly
rapidly. They have long antennae and either two fairly long tails or a
pair of forceps-like structures at the end of the abdomen. They are
terrestrial and are found chiefly under stones in humid and shady
situations. Fig. 21 shows a common campodeid, a species of _Campodea_,
occurring commonly in Illinois.
The Diplura feed on fungi and other soil microorganisms. Although they
are found most frequently under stones, they live also in the soil and
in matted leaves or duff on the floor of woods. About a dozen species of
Diplura occur in Illinois.
Protura
Proturans
Minute, wingless, blind insects that never grow to more than 0.05 inch
long. They have no antennae and use the front legs to some extent for
feeling. They are terrestrial and are found inhabiting dead twigs and
leaves on the forest floor. Fig. 22 shows _Acerentulus barberi_ Ewing, a
member of a genus which occurs in many localities in Illinois. Only a
few species of proturans have been taken in the state.
Collembola
Springtails
Small, wingless insects that jump and crawl when disturbed. They have
short antennae and usually a springing structure on the under side near
the posterior end of the body. They live in moist places and are
abundant under leaf mold and similar material. Illustrated in fig. 23 is
_Achorutes armatus_ Nicolet, which often becomes a major pest in
mushroom cellars and greenhouses.
About a hundred different species of Collembola occur in Illinois; they
include some of our smallest insects. A few never grow longer than 0.007
inch; the largest approach half an inch in length. These hardy animals
are active all year and are surprisingly resistant to cold. Certain
species occur on snow in winter. In Illinois a small, bluish gray
species, _Podura aquatica_ Linnaeus, is found on the surface of still
water at the margins of ponds and small streams.
Microcoryphia
Bristletails
Wingless, somewhat cylindrical insects that run and jump with extreme
rapidity. They have long antennae and three long tails. The under side
of the abdomen bears several pairs of short projections called styli,
which are vestiges of abdominal legs. Bristletails live in rocky places
or in ground cover. A type occurring in some parts of Illinois is shown
in fig. 24. It often occurs on rocky exposures, where it resembles the
lichens and is difficult to detect.
[Illustration: Fig. 23.—Collembola. _A_, _Isotoma andrei_; _B_,
_Achorutes armatus_; _C_, _Neosminthurus clavatus_. _A_ and _C_ are
found in woodland leaf molds; _B_ is frequently abundant in
commercial mushroom cellars. Actual length of adults ranges from
0.03 to 0.05 inch. (Drawings _A_ and _C_ after Harlow B. Mills.)]
[Illustration: Fig. 24.—Microcoryphia. A bristletail belonging to
the genus _Machilis_, often found on lichen-covered, shaded rocks.
Actual length including tail is sometimes 0.5 inch. (Drawing after
R. E. Snodgrass.)]
[Illustration: Fig. 25.—Thysanura. _Thermobia domestica_, a common
Silverfish. Actual length about 0.3 inch.]
Thysanura
Silverfish
Wingless, flat insects that run rapidly. They have long antennae and
three long tails. They are terrestrial and are commonly found in
dwellings. Fig. 25 shows one of the common Silverfish, _Thermobia
domestica_ (Packard); it frequently eats book bindings and other starchy
materials. Some out-of-door rare forms live in the soil and are seldom
collected.
Primitive Winged Insects
The primitive winged insects cannot fold their wings, which in repose
are held erect over the body or straight out from the sides, as
illustrated in figs. 26 and 29. Although many types of these insects
lived in bygone ages, only two orders have survived to the present. Both
occur abundantly in Illinois.
Ephemeroptera
Mayflies
A group of insects in which the nymphs or young live in streams and
lakes; the adults are found along the edges of the streams or lakes from
which they have emerged. Mayflies are unique in that the full-grown
nymphs molt into winged insects that are not quite mature and that molt
again, usually the next day, when they emerge as fully mature adults.
The nymphs are varied in shape and have short antennae, long legs, which
are often flattened, and three tails at the end of the body. The adult
flies have very long front legs, short antennae, practically no
mouthparts, usually two pairs of wings, and two or three long tails.
When a mayfly is at rest, the wings are held together above the body.
_Hexagenia limbata_ (Serville), figs. 26 and 27, is one of the very
common Illinois mayflies and is an important factor in the food economy
of many fish.
Mayflies, formerly called Plectoptera, together with stoneflies,
caddisflies, and midges, constitute a very large portion of the life of
our lakes and streams; all four groups are important as fish food.
Odonata
Dragonflies, Damselflies
Another order in which the nymphs develop in streams, lakes, or ponds,
and in which the adults are aerial. The nymphs have short antennae, long
legs, and either a stout body with no tail, as in _Anax junius_ (Drury),
fig. 28 (dragonfly nymph), or a slender body with three large leaflike
gills projecting from the end of the body (damselfly nymph). A most
distinctive feature of this order is an extensile, highly modified lower
lip that fits like a mask over the face of a nymph. The lower lip is
hinged to extend forward and seize the small animals upon which the
nymph lives. The adults are large, often beautifully colored, as is the
_Tramea lacerata_ Hagen, fig. 29. They have chewing mouthparts and two
pairs of large wings, very finely and intricately netted with veins.
[Illustration: Fig. 26.—Ephemeroptera. _Hexagenia limbata_, the
adult form; this mayfly is also called shadfly or willowfly.
Mayflies sometimes emerge in great swarms and congregate in piles
around bridge or city lights. Actual length about 1.0 inch.]
[Illustration: Fig. 27.—Ephemeroptera. _Hexagenia limbata_, the
nymphal form of the mayfly in fig. 26; in this stage the mayfly
lives in water, emerging when full grown. Actual length about 1.0
inch.]
The order is divided into two types; the adult flies are told apart as
follows:
Body stout, wings broad at base, the front and Suborder
hind wings different in shape. Strong fliers. Anisoptera
Dragonflies
Body slender, wings narrowed at base, the front Suborder Zygoptera
and hind wings similar in shape. Weaker fliers
than dragonflies but nonetheless elusive.
Damselflies
[Illustration: Fig. 28.—Odonata. Nymph of _Anax junius_, a dragonfly
widely distributed in Illinois. Actual length of full-grown nymph
about 2.3 inches. (Drawing courtesy of C. O. Mohr.)]
[Illustration: Fig. 29.—Odonata. _Tramea lacerata_, a dragonfly
commonly found near ponds and drainage ditches in Illinois.
Wingspread about 3.2 inches. (Drawing courtesy of C. O. Mohr.)]
Folding-Wing Insects
Almost all insects in this category can fold their wings in repose back
over their bodies, as illustrated in fig. 31. A few kinds, notably some
of the moths and butterflies, have lost this wing action and in repose
hold their wings erect. In some of these kinds, the male is winged and
the female is wingless; in others, certain generations may be wingless
and others winged; and, in still others, the species may be wingless in
all stages. No members of the orders of folding-wing insects molt after
becoming winged or sexually mature.
[Illustration: Fig. 30.—Cursoria. _Supella supellectilium_, the
brown-banded cockroach. Actual length about 0.6 inch. (Drawing
courtesy of C. O. Mohr.)]
[Illustration: Fig. 31.—Cursoria. _Stagmomantis carolina_, a praying
mantis. Common in southern and central Illinois. Actual length of
adult about 1.5 to 2.0 inches.]
[Illustration: Fig. 32.—Cursoria. _Diapheromera femorata_, a
walkingstick insect. This insect lacks wings. Actual length about
3.0 inches. (Drawing courtesy of C. O. Mohr.)]
Cursoria
Cockroaches, Mantids, Walkingsticks
An order that includes three groups of terrestrial insects, each group
markedly different in appearance from the others: (1) rapidly running
insects usually having two pairs of wings, each with a dense network of
fine veins, the front pair of wings thick and leathery, fig. 30
(cockroaches); (2) winged insects having long, grasping front legs, fig.
31 (praying mantids); and long, wingless insects resembling sticks, fig.
32 (walkingsticks). The mouthparts are fitted for chewing. The young
look and act like the adults except that they do not have wings. The
cockroaches are omnivorous, feeding chiefly on organic foods rich in
carbohydrates, or on fungus growth. Cockroaches are among our most
persistent indoor pests, eating a wide variety of domestic foods. The
praying mantids feed on other insects, which they capture in their
enlarged front legs. The walkingsticks eat leaves. The cockroaches and
mantids lay eggs that are glued together and form pods or capsules, each
containing 30 or more eggs. The walkingsticks lay their eggs singly.
[Illustration: Fig. 33.—Isoptera. _Reticulitermes flavipes_, the
commonest kind of termite found in Illinois: _A_, first form queen
with wings spread, many times natural size (this is the form that
lays eggs); _B_, worker nymph, natural size; _C_, first form queen,
approximately natural size, with wings placed in their natural
resting position. (Drawing courtesy of C. O. Mohr.)]
[Illustration: Fig. 34.—Orthoptera. _Melanoplus bilituratus_, the
migratory locust, a common Illinois grasshopper. Actual length about
1.0 inch.]
Isoptera
Termites
Fragile or soft insects with chewing mouthparts. The mating forms are
dark brown and have two similar pairs of wings; both pairs are delicate
and have a fine network of veins. The workers are white and soft bodied.
Termites, which live in colonies in wood, are also called “white ants,”
although they are not true ants. The common native species in Illinois
is _Reticulitermes flavipes_ (Kollar), fig. 33, which lives in rotten
logs and is destructive to buildings of wooden construction throughout
Illinois; it is most destructive in the southern part of the state.
[Illustration: Fig. 35.—Orthoptera. _Ceuthophilus maculatus_, a
wingless cave cricket. Crickets of this kind are found in caves,
under rocks, and in basements. Actual length about 1.0 inch.]
[Illustration: Fig. 36.—Dermaptera. _Labia minor_, an earwig
frequently abundant in Illinois. Actual length of adult about 0.2
inch.]
Orthoptera
Grasshoppers, Crickets
Terrestrial insects usually with two pairs of wings, each wing with a
very fine, dense network of veins, the front pair thick and leathery,
the hind pair delicate and fanlike. The mouthparts, fitted for chewing,
have stout mandibles. The young look and act like the adults but do not
have wings. This order includes all the grasshoppers, crickets, and
katydids. Fig. 34 shows the migratory locust or grasshopper, _Melanoplus
bilituratus_ (Walker). Adults of several of the groups of Orthoptera
never develop wings. These include such odd forms as the cave crickets,
exemplified by _Ceuthophilus maculatus_ (Harris), fig. 35.
Dermaptera
Earwigs
Insects with two pairs of wings, the front pair forming short, hard
covers, the second pair large, membranous, many-veined, and in repose
folded intricately beneath the front pair. The abdomen ends in a pair of
pincer-like structures. A common Illinois form is _Labia minor_
(Linnaeus), shown in fig. 36. Of the half-dozen species known from
Illinois, all but one were originally from Europe or Asia. Earwig
females lay eggs in chambers in the ground and guard them.
[Illustration: Fig. 37.—Plecoptera. _Isoperla confusa_, one of the
typical stoneflies found in Illinois; adult form. Actual length
about 0.8 inch. Illinois stoneflies range in length from 0.25 inch
to 1.5 inches.]
[Illustration: Fig. 38.—Plecoptera. _Isoperla confusa_; the nymph of
the species shown in fig. 37. The nymph lives in streams. Actual
length about 0.6 inch.]
Plecoptera
Stoneflies
Insects that pass the young or nymphal stage in streams. They have
slender, soft bodies and long tails; they move about rapidly. The adults
are terrestrial in habit and occur along streams. In most species, the
adults have two pairs of wings that are folded flat over the back; the
number of crossveins varies from many to few. The antennae are long; the
mouthparts are of the chewing type but greatly reduced. Of exceptional
interest are stonefly adults that emerge in winter and are active from
November through March. The winter forms can often be collected on
bridges. Figs. 37 and 38 illustrate a spring species, _Isoperla confusa_
Frison.
Zoraptera
Zorapterans
Small, whitish insects, about a twelfth of an inch long, that run
rapidly. They live in small colonies in rotting sawdust, in rotten logs,
and under the bark of stumps. They have fairly long antennae, chewing
mouthparts, and a pair of short, inconspicuous tails. Most members of a
colony are wingless, but occasionally there occurs a darker specimen
having two pairs of wings. These wings have only a few veins. In
Illinois only a single rare species has been found; it is called
_Zorotypus hubbardi_ Caudell, fig. 39.
Corrodentia
Booklice, Barklice
Small, rounded or flattened insects, rarely a quarter-inch long, usually
about 0.13 inch. In many species, adults have two pairs of wings, which
have only a few zigzagging veins. Winged forms, such as _Psocus
striatus_ Walker, fig. 40, are found in crevices of bark and on dead
leaves. Common species found in houses and on stored grain are usually
wingless and louselike, similar in general appearance to fig. 41.
Corrodentia eat fungus growth on bark, dead leaves, moldy grain, damp
books, and similar materials. Some of the outdoor species become very
abundant on drying corn leaves during autumn and may breed in immense
numbers. They do little harm, feeding chiefly on fungus strands.
Phthiraptera
Chewing Lice, Sucking Lice
Wingless, blind, flattened insects with short antennae, short legs,
inconspicuous mouthparts, and no tails on the posterior end of body.
They are found exclusively on the bodies of birds and other warm-blooded
animals. The young have the same general shape and habits as the adults
and are found with them. Illinois species of lice belong to two distinct
suborders, which may be differentiated through use of the following key:
[Illustration: Fig. 39.—Zoraptera. _Zorotypus hubbardi_, the only
zorapteron recorded from Illinois. The specimen on the left is a
winged adult female; the specimen on the right is a wingless adult
female. Actual length of adults about 0.08 inch.]
[Illustration: Fig. 40.—Corrodentia. _Psocus striatus_, a common
bark louse found on many trees. Actual length 0.2 inch.]
[Illustration: Fig. 41.—Phthiraptera. Suborder Mallophaga.
_Cuclotogaster heterographus_, a chewing louse found on the heads of
poultry. Actual length about 0.1 inch.]
[Illustration: Fig. 42.—Phthiraptera. Suborder Anoplura.
_Haematopinus asini_, the blood-sucking horse louse. Actual length
0.1 inch.]
Legs fitted for running, as in fig. 41, without Suborder
large pincers at their ends; mouthparts situated Mallophaga
near the middle of under side of the head and
fitted for chewing. Occurring on birds and
mammals. The chewing lice
Legs fitted for clinging to hairs, each leg Suborder Anoplura
ending in a large pincer, as in fig. 42;
mouthparts retracted within head, consisting of a
set of thin, needle-like parts fitted for sucking
blood. Normally occurring only on mammals. The
sucking lice
_Suborder Mallophaga._
Individuals of many species of chewing lice move about with considerable
rapidity. Many of them are very prettily banded and colored, as is the
chicken head louse, _Cuclotogaster heterographus_ (Nitzsch), fig. 41.
Anyone who has worked with domestic fowls or animals has seen members of
this order scurrying among the feathers or hair. These insects feed on
what they can chew from the surface of the skin and in some cases are
known to injure their hosts.
_Suborder Anoplura._
The sucking lice are sluggish insects that usually cling to hairs. Human
lice are often found clinging to clothing. Various species occur on
native and domestic species of mammals in Illinois. Fig. 42 shows the
horse louse, _Haematopinus asini_ (Linnaeus).
Thysanoptera
Thrips
[Illustration: Fig. 43.—Thysanoptera. _Thrips tabaci_, onion thrips.
Actual length less than 0.1 inch.]
Small, active insects, usually about 0.1 inch long, rarely a
quarter-inch long, very slender, usually each with two pairs of narrow
wings and with the under side of the head forming a sharp, conelike
sucking structure. Each wing has a long fringe on the hind margin; each
front wing may have one or two veins running the length of the wing. The
young of these insects are somewhat similar to the adults but are softer
bodied. Fig. 43 shows an adult of _Thrips tabaci_ Lindeman, the onion
thrips. Thrips suck the juice from plants. Because of their minute size,
they are seldom noticed, but they can be collected in large numbers from
blossoms of almost any plant. A few species of thrips, such as the onion
thrips and the privet thrips, attack agricultural or horticultural
plants and inflict considerable damage. A few species occasionally bite
human beings.
Hemiptera
True Bugs and Their Allies
Insects usually with two pairs of wings and with the mouthparts formed
for sucking. The order contains two distinct suborders, the Heteroptera
and the Homoptera. All species of Hemiptera in North America fall
readily into one suborder or the other, but certain species in other
parts of the world are intermediate between the two suborders.
[Illustration: Fig. 44.—Hemiptera. A typical stink bug of the family
Pentatomidae, showing attachment of beak and arrangement of wings.
Actual length about 0.4 inch.]
In the suborder Heteroptera, containing the stink bugs, the chinch bugs,
and their allies, the beak is attached to the under side of the front
part of the head; the base of the front pair of wings is hardened, and
only the apical portion is membranous or delicate; the entire hind pair
is delicate. In repose, the wings are folded over and flat against the
body, the hind pair underneath. These characters are shown in fig. 44,
which pictures a stink bug belonging to the family Pentatomidae. The
young have the same general appearance and habits as the adults, but
they lack wings. This suborder includes many common kinds, such as the
water bugs, the water striders (these seldom develop wings even in the
adult stage), the ambush bugs, and the lace bugs, as well as the stink
bugs and the chinch bugs. The chief pest of this group is the chinch
bug, _Blissus leucopterus_ (Say), fig. 45. Other pests include many
kinds of plant bugs, of which _Lygus lineolaris_ (Beauvois) is shown in
fig. 46. The bed bugs, another group never developing functional wings,
also belong in this suborder.
[Illustration: Fig. 45.—Hemiptera. _Blissus leucopterus_, the chinch
bug. Actual length about 0.1 inch.]
[Illustration: Fig. 46.—Hemiptera. _Lygus lineolaris_, the tarnished
plant bug. Actual length about 0.2 inch.]
[Illustration: Fig. 47.—Hemiptera. _Anuraphis maidiradicis_, the
corn root aphid. The form at the left is the winged form; that at
the right is the wingless form. All of the plant lice have these two
forms. This species, as well as other kinds of plant lice, is
frequently attended by ants, which feed on the honeydew produced by
the aphids. Actual length less than 0.1 inch.]
Members of one family, the Reduviidae or assassin bugs, prey on other
insects. A few species called kissing bugs, some of them an inch long,
occasionally attack people, inflicting an extremely painful bite and
causing considerable bleeding.
[Illustration: Fig. 48.—Hemiptera. _Aspidiotus perniciosus_, the
destructive San Jose scale. The scale is cut away on upper specimen
to show insect proper beneath. Diameter less than 0.1 inch.]
[Illustration: Fig. 49.—Hemiptera. _Empoasca fabae_, the potato
leafhopper. This species is pale green. Some species are
distinguished by bright red or yellow markings. Actual length about
0.1 inch.]
[Illustration: Fig. 50.—Megaloptera. The larva of a species of
_Sialis_, an alderfly. This form is aquatic. Actual length 0.7
inch.]
[Illustration: Fig. 51.—Megaloptera. The adult of _Sialis mohri_, an
alderfly. Other members of this order reach a length of 1 or 2
inches. They are mostly black, black and white, or mottled gray in
color. Actual length 0.5 inch.]
The suborder Homoptera contains the cicadas, aphids, and their allies.
All these insects have sucking mouthparts, but in each the beak is
attached at the back of the head instead of the front of the head as in
the suborder Heteroptera. In many species of the Homoptera, each
individual has two pairs of wings, both of which are membranous.
Probably as many species are without wings, however, as with them. The
nymphs are in most respects similar to the adults. Sexual characters,
and in some forms wings, gradually develop as the insects approach the
adult stage, when development is complete.
[Illustration: Fig. 52.—Neuroptera. _Chrysopa nigricornis_, a green
lacewing. When handled, members of this genus give out a very
penetrating and disagreeable odor. Actual length 0.6 inch.]
[Illustration: Fig. 53.—Neuroptera. A larva of the genus _Chrysopa_.
This form uses the long jaws to impale aphids and suck their body
juices. Actual length 0.5 inch.]
This suborder contains a large number of economic pests, including scale
insects and leafhoppers, as well as many aphids. In many species of
aphids each insect has a pair of tubular structures near the end of the
body; these are called cornicles and can be seen in fig. 47, showing the
corn root aphid, _Anuraphis maidiradicis_ (Forbes). In most species of
scale insects each individual produces a tough scale, which covers and
protects its delicate body, as in fig. 48, showing the destructive San
Jose scale, _Aspidiotus perniciosus_ Comstock. Leafhoppers of many
kinds, such as _Empoasca fabae_ (Harris), fig. 49, are among the
destructive pests of beans, potatoes, grapes, apples, and other plants.
The treehoppers, spittlebugs, and lanternflies also belong to this
suborder.
Megaloptera
Alderflies, Dobsonflies
In this and in the following orders of insects, the life history
includes four distinct stages, the egg, the larva, the pupa, and the
adult. In the Megaloptera, which include alderflies and dobsonflies, the
larvae are caterpillar-like or grublike, and the pupae represent a
transformation stage in which the tissues of the larvae are converted to
those of the adults. The larvae never have external wing pads; in winged
species, these pads first appear externally in the pupae. The adults
have long antennae, two similar pairs of net-veined wings, and chewing
mouthparts. They are moderately strong fliers. The larvae, fig. 50, live
in streams and lakes; when fully grown they migrate to dry land and
pupate in the ground or under the bark of rotten logs.
Typical of the appearance of Illinois alderflies is the adult of _Sialis
mohri_ Ross, shown in fig. 51. Well known to the fisherman is the
hellgrammite, the tough, ferocious, leathery larva found under rocks in
streams and prized for bait. This larva matures into the large
dobsonfly, _Corydalis cornuta_ (Linnaeus), which often attains a
wingspread of 4 inches.
Neuroptera
Lacewings and Their Allies
Insects with two pairs of wings, both pairs about the same size and
shape and intricately netted with veins; antennae long and slender,
mouthparts fitted for chewing, posterior end of body without tails. The
green lacewings, including _Chrysopa nigricornis_ Burmeister, fig. 52,
are our commonest members of this order. The young or larvae of this
order are entirely unlike the adults and are somewhat grublike in form.
The aphid lion, the interesting larva of _Chrysopa_, fig. 53, is
frequently collected by the sweeping method. Another interesting larva
of this order is the doodlebug or ant lion, of Huckleberry Finn fame.
The adult insects that mature from these ant lion larvae are very
similar in appearance to the chrysopids or lacewings. The larva of each
of these insects sinks its long, sharp, curved mandibles into the body
of its prey and sucks out the body juices. The female _Chrysopa_ has the
curious habit of forming a long, slender stalk under each egg; the
bottom of the stalk is fastened to the upper side of a leaf. The stalks
are thought to have the effect of keeping the first larvae of a hatch
from devouring the eggs placed nearby.
When the larva is mature, it spins a globular, silken cocoon or cell
around itself and in this changes into the pupal, or quiescent, stage.
While the pupa itself does not appear active, within it the larval
tissues are reorganized into the structures of the adult, and the final
growth of the wings and reproductive organs occurs. When this change is
completed, the adult insect emerges from the cocoon.
[Illustration: Fig. 54.—Coleoptera. _Copris minutus_, one of the
scarab beetles. The drawing shows one of the elytra upraised and
illustrates the method of folding the hind pair of wings under the
elytra. Actual length 0.4 inch.]
[Illustration: Fig. 55.—Coleoptera. A weevil belonging to the genus
_Curculio_, which feeds on nuts and acorns. In this genus the beak
is exceptionally long. In most of the Illinois weevils the beak is
shorter and stouter. Actual length 0.4 inch.]
Coleoptera
Beetles, Weevils
Insects with two pairs of wings, the second pair delicate and folded
under the first pair, which are hard and thickened and folded back
against the body, touching each other along the midline to form a hard
shell, as shown in _Copris minutus_ (Drury), fig. 54. The upper wings
are not used for locomotion, but form part of the body armor and are
called _elytra_. In most beetles they cover the entire posterior part of
the body; in many others they are abbreviated and cover only part of the
abdomen. The immature stages of the beetles are wormlike or grublike and
have a great variety of food habits. Some of them defoliate plants,
others attack roots, and still others feed on other insects.
A great many of the serious insect pests, including kinds that attack
field crops, stored products, and household goods, are beetles. Beetles
of one group having the front of the head produced into a snoutlike
structure, as in the genus _Curculio_, fig. 55, are called weevils or
snout beetles. This group has maggot-like larvae and contains many of
our worst pests, such as the plum curculio, cotton boll weevil, alfalfa
weevil, and clover weevil. Bizarre and striking forms occur in many
beetle groups, notably among the scarab and long-horn beetles. The
largest in Illinois is the rhinoceros beetle, _Dynastes tityus_
(Linnaeus); the males (one shown on the cover of this circular) have
long projections on both head and thorax; the larvae live in rotten
wood.
Tree-boring beetle larvae are destructive to many orchard, ornamental,
and native trees. These include chiefly the round-headed borers, adults
of which are long-horn beetles; flat-headed borers, adults of which are
metallic wood borers; and engraver or shot-hole types, adults of which
are small and bullet shaped and are called bark beetles.
In a few families of beetles, both the adults and larvae are fitted for
aquatic life. Well known among these are the shining whirligig beetles.
Hymenoptera
Bees, Wasps, Ants, Sawflies
Insects typically with two pairs of wings; antennae of various lengths;
chewing mouthparts; without tails. A typical member of this group is the
wasp _Vespula maculata_ (Linnaeus), fig. 56. Many adult members of the
group are atypical in that they lack wings; these include all the true
ants, fig. 57, which are without wings except for the sexual forms
produced at the time of the nuptial flights. Forms of one species,
_Lasius interjectus_ Mayr, are shown in fig. 58. The wings, when
developed, are without scales; the venation is much less extensive than
in the Neuroptera; and the hind wings differ in shape and size from the
front wings. The young stages of the Hymenoptera are caterpillar-like or
grublike, entirely different from the adults.
This very large order includes such well-known forms as the bees, as
well as the wasps and the ants, mentioned above. In addition, it
includes the sawflies, whose caterpillar-like larvae are extensive
defoliators of a large number of native and cultivated plants and
shrubs; the large and varied groups of parasitic wasps that exert great
influence in the natural control of a tremendous number of other
insects; and a large number of gall-making wasps, whose galls are
especially conspicuous on oak trees. A parasitic wasp of the genus
_Opius_ is shown in fig. 59. The parasitic wasps are extremely diverse
in size, shape, and habits. They range in size between 0.02 and 2.0
inches.
[Illustration: Fig. 56.—Hymenoptera. _Vespula maculata_, the common
bald-faced hornet. Actual length 0.8 inch.]
[Illustration: Fig. 57.—Hymenoptera. A worker ant belonging to the
genus _Formica_. This form lacks wings. Actual length 0.3 inch.]
Mecoptera
Scorpionflies
Insects typically with two similar pairs of delicate wings, each wing
with a network of veins. In repose the wings are laid either tentlike
over the back or almost flat. The mouthparts are fitted for chewing and
usually are lengthened into a beaklike structure, as in _Panorpa
chelata_ Carpenter, fig. 60. The larvae, seldom found, live in damp
woods. The adults of most winged species occurring in Illinois are about
0.5 inch long. They are active in early summer in shady woods, flying
through the undergrowth. Adults of the genus _Boreus_ are smaller and
they have very short, veinless wings. They emerge in the winter and
early spring; these little metallic black insects often hop around on
late winter snow. In certain genera, the adult male genitalia form a
bulb-like structure at the end of the body, as in fig. 60. This
structure is harmless but, because it resembles a scorpion’s sting,
insects of these genera are given the name scorpionflies.
[Illustration: Fig. 58.—Hymenoptera. _Lasius interjectus_, a
harmless winged ant, the yellow ant, with which the winged termite
is often confused: _A_, queen with wings spread, many times natural
size; _B_, worker ant, natural size; _C_, queen, approximately
natural size, with wings partially closed and as usually seen. Ant
has a narrower waist and shorter wings than termite. Actual length
of queen about 0.3 inch.]
[Illustration: Fig. 59.—Hymenoptera. A parasitic wasp, _Opius_, sp.
Actual length 0.1 inch. (Drawing from U. S. D. A.)]
[Illustration: Fig. 60.—Mecoptera. _Panorpa chelata_, one of about
15 Illinois species of scorpionflies. Only the male has the
“scorpion” tail. Actual length of insect about 0.5 inch.]
Trichoptera
Caddisflies
Insects with two pairs of wings, poorly developed mouthparts of the
chewing type, and long antennae; without tails on the posterior end of
the body. In repose, the wings are held rooflike over the body and have
only a moderate number of longitudinal veins, which are not connected by
crossveins into any resemblance of a network. Neither body nor wings are
covered with scales. The larvae are wormlike and they live in streams,
ponds, and lakes. Many of them build cases of sticks, stones, or sand
and move about with only the front end of the body protruding from the
case. When disturbed, the larvae withdraw completely into the cases and
are then very difficult to see. The adult fly and larva of _Rhyacophila
fenestra_ Ross illustrate this order, figs. 61 and 62. In many aquatic
situations, caddisflies are the predominant small animal life and are an
important factor in fish food economy. Also, they are stream pollution
indicators.
[Illustration: Fig. 61.—Trichoptera. _Rhyacophila fenestra_; the
adult form of this caddisfly is shown here. Actual length about 0.4
inch.]
[Illustration: Fig. 62.—Trichoptera. _Rhyacophila fenestra_; the
larva, shown here, is aquatic and builds no case. The larvae of some
other kinds of caddisflies live in cases made of sticks and stones.]
Lepidoptera
Butterflies, Moths
Insects typically with two pairs of wings, with long antennae, and with
mouthparts forming a long sucking tube. The body and wings are covered
with a dense mass of scales, which are characteristic of this order,
fig. 63. The young are known as caterpillars or grubs. The larval stage
in this order is well exemplified by the fairly smooth, cylindrical
caterpillar of the fall armyworm, _Laphygma frugiperda_ (Smith),
fig. 64. Some other larvae are hairy; still others are sluglike.
[Illustration: Fig. 63.—Lepidoptera. A typical moth, showing scales
on wings and body, and sucking tube, which is coiled up under the
head when not in use. Species of this order occurring in Illinois
include specimens that vary in size from 0.1 inch to several inches.
The largest of these insects have a wingspread of over 5 inches.]
To this order belong not only a very large number of species, but also a
very large number that are especially injurious to agriculture. These
include such species as the codling moth, cabbage moth, butterflies, the
entire cutworm group, and a host of others. In addition, the various
clothes moths, which are a constant source of loss to householders, and
various species of meal moths, which cause tremendous damage to stored
grain every year, are members of this order.
[Illustration: Fig. 64.—Lepidoptera. _Laphygma frugiperda_, the fall
armyworm: _A_, egg mass on leaf; _B_, top and side view of
individual eggs; _C_, adult; _D_, larva; _E_, pupae. Wing span of
adult about 1.5 inches. (Drawing from U. S. D. A.)]
In one group of moths, there are clear “windows” on the wings, but these
are always surrounded by areas or lines of scales. A few species of the
Lepidoptera are very odd in having wingless females. Examples are the
bagworms and some of the cankerworms. In these species, however, the
body of the female is densely clothed with scales, which will serve to
identify her as one of the Lepidoptera.
The habits of Lepidoptera larvae are very diverse. Most of these larvae
are leaf eaters, but some bore into trunks of trees and stems of
herbaceous plants. Some of the small ones mine within leaf tissue,
others live in the ground, where they eat roots, and a few are aquatic,
living in clear, rapidly flowing streams.
Diptera
Flies, Mosquitoes, and Their Allies
Insects with only one pair of wings, each wing with a limited number of
veins. Other characters of the order, including antennae and mouthparts,
are extremely varied. Most immature stages are wormlike or maggot-like.
They live in protected situations, such as within the tissues of a
plant, in water, in leaf mold, or in the tissues of animals. A typical
life cycle is that shown for the house fly, _Musca domestica_ Linnaeus,
fig. 65. The ubiquitous house fly is undoubtedly the best known
representative of this order. It is also one of the most persistent and
dangerous insect pests, being a possible carrier of many diseases.
[Illustration: Fig. 65.—Diptera. _Musca domestica_, the house fly.
The fly has only a single pair of wings; the pale, maggot-like larva
is without legs; the darker, egg-shaped puparium contains the pupal
or quiescent stage. Length of adult 0.2 inch. (Drawing by Alice Ann
Prickett.)]
Mosquitoes, punkies, black flies, and horse flies are likewise well
known members of this order. In addition to economic forms, the order
Diptera includes midges, crane flies, bee flies, robber flies,
bluebottle flies, and a great assortment of other kinds of insects.
Interesting are the bee flies, which mimic other insects such as honey
bees, bumble bees, and wasps to an extent that wins them immunity from
the attention of many beginning collectors.
Siphonaptera
Fleas
Wingless insects that evolved from folding-wing insects; conspicuously
flattened from side to side; with stout spiny legs, and with numerous
spines over the body; without conspicuous antennae or tails or a forked
posterior appendage like that of the springtails; usually hard; ranging
in color from yellowish brown to almost black.
The human flea, _Pulex irritants_ Linnaeus, and a widespread Illinois
rat flea, _Nosopsyllus fasciatus_ (Bosc), are shown in fig. 66.
All the fleas, which feed on the blood of birds and other animals, have
sucking mouthparts. They are powerful jumpers. The young stages are
slender, white larvae, fig. 67, which live in the nests of various
animals; these larvae are seldom collected. The fleas are found on the
animals themselves or around their nests. Several species of fleas,
including the cat and dog flea, the human flea, and the rat fleas,
attack man. One of the rat fleas, _Xenopsylla cheopis_ (Rothschild) is
the common transmitter of the organism causing bubonic plague.
[Illustration: Fig. 66.—Siphonaptera. _Pulex irritans_, human flea
(left), and _Nosopsyllus fasciatus_, one of the rat fleas. Actual
length of body about 0.1 inch.]
[Illustration: Fig. 67.—Siphonaptera. Larva of flea found in mouse
nest. Length about 0.12 inch.]
RELATIVES OF INSECTS
There are many small animals that belong to the same general group as
insects and that are frequently collected with them. Spiders,
centipedes, and amphipods are a few of many examples of such animals.
Together with insects, they form the animal phylum called Arthropoda,
characterized by having segmented bodies and jointed legs. A brief
description is included here of the common groups of these insect
relatives found in Illinois.
Isopoda
Sowbugs, Pillbugs
Convex, many-legged animals having conspicuous antennae; several of the
posterior segments short and joined rather closely to form an abdomen.
Of the Illinois forms, about one-half are aquatic, living in streams and
ponds. The others live in terrestrial situations that are humid and
dark. They are frequently found under boards and in soil in greenhouses.
One species of this group is _Armadillidium vulgare_ (Latreille), fig.
68, which possesses the ability to curl up in a hard shell-like ball
when disturbed. The isopods, relatives of crabs, shrimps, and crayfish,
belong to the general group known as crustaceans. The crustacean groups
are abundant in the ocean. In past geologic ages, the early ancestors of
such predominantly terrestrial groups as insects and spiders resembled
ancestors of the present crustacean marine forms.
[Illustration: Fig. 68.—Isopoda. _Armadillidium vulgare_, a common
pillbug or sowbug (two views). Actual length 0.3 inch. (Drawings
from U.S.D.A.)]
Amphipoda
Small Water Shrimps
Humpbacked, many-legged crustaceans, fig. 69, that are, unlike the
isopods, flattened from side to side like the fleas. They are all
aquatic but are seldom found swimming in open water; they prefer to live
in tangled masses of vegetation, under stones or logs, and among debris
in the very shallow water where it touches the bank. These little
shrimps are never more than about one-half inch long and are frequently
collected in large numbers along with aquatic beetles. As is the case
with the aquatic sowbugs, certain species of amphipod shrimps occur in
subterranean water sources and frequently are found in wells. Most of
these species are blind.
[Illustration: Fig. 69.—Amphipoda. _Gammarus_ sp., a common small
water shrimp. Actual length 0.4 inch.]
[Illustration: Fig. 70.—Scorpionida. _Centruroides vittatus_, the
only scorpion known to occur in Illinois. Actual length 2.0 inches.
(Drawing by Alice Ann Prickett.)]
Scorpionida
Scorpions
Animals belonging to the spider group; characterized by a pair of stout
pincers at the end of each front leg and a long tail-like extension of
the abdomen ending in a sharp sting, as in _Centruroides vittatus_
(Say), fig. 70. They have fairly long bodies and five pairs of legs
each, including the chelate pair. During the day they live under stones
and bark, moving about at night in search of insects and other small
organisms on which they prey. Many species occur in the Southwest; the
range of one of these extends as far northeastward as southwestern
Illinois.
Pseudoscorpionida
Pseudoscorpions
Animals belonging to the spider group; characterized by a pair of stout
pincers at the end of the front legs, as in _Larca granulata_ (Banks),
fig. 71. They have short, stout bodies, each with five pairs of legs
including the chelate front pair, but unlike the true scorpions they
have no tails or stings. The pseudoscorpions are sometimes found indoors
in old books, looking for their prey of small insects. They occur in
greater numbers in wooded areas.
[Illustration: Fig. 71.—Pseudoscorpionida. _Larca granulata_, a
native Illinois pseudoscorpion. Actual length 0.1 inch.]
Phalangida
Daddy Longlegs, Harvestmen
Spider-like forms, each animal with a short, round body and four pairs
of walking legs that in most species are very long, fig. 72. They occur
chiefly in woods and may be found in numbers walking over foliage and
logs; they are often found on bluffs and in shady places. They feed on
decaying humus. A few Illinois forms that occur chiefly on bark have
considerably shorter legs than the species that range more widely.
[Illustration: Fig. 72.—Phalangida. A common harvestman or daddy
longlegs. Actual length of body 0.3 inch.]
Araneida
Spiders
Varied and well-known animals, each with four pairs of walking legs and
a body divided into a cephalothorax (which combines the head and thorax)
and abdomen. The spiders present a tremendous variety of shapes, some
being round and fat, like the black widow, _Latrodectus mactans_
(Fabricius), fig. 73, others being long and slender, mimicking ants.
Others are crablike in shape; some that are long and slender are
extremely rapid in their movements. Spiders appear practically
everywhere. Certain species are domestic and are found only in houses.
In Illinois the only poisonous species of any importance are the black
widow spider, which is found in a variety of situations, and the recluse
spider, _Loxosceles reclusa_ Gertsch & Mulaik, which has been found in
house basements in southern Illinois.
[Illustration: Fig. 73.—Araneida. _Latrodectus mactans_, the black
widow spider. Actual length of body 0.4 inch.]
Acarina
Ticks, Mites
Animals somewhat like the spiders but having no marked division between
the cephalothorax and the abdomen. Each adult has four pairs of walking
legs, although an individual of the very young stages has only three
pairs. The mites are generally very minute and seldom are seen by the
beginning collector. They vary greatly in general appearance. Many
species are extremely destructive to stored produce, to live domestic
animals, and to many groups of plants. Adults of the harvest mite and
early stages of the chigger mite attack man persistently.
[Illustration: Fig. 74.—Acarina. _Dermacentor variabilis_, the
common dog tick of Illinois and vector of Rocky Mountain spotted
fever. When engorged, the tick looks like a red berry. Actual length
0.2 inch. (Drawing from U. S. D. A.)]
Ticks are larger than mites. All the species feed on warm-blooded
animals, including birds and mammals. The commonest Illinois tick is
_Dermacentor variabilis_ (Say), fig. 74, which transmits the organism
causing the often fatal disease called Rocky Mountain spotted fever.
Although this disease occurs only infrequently in Illinois, hikers and
others exposed to ticks on excursions into the out-of-doors should
carefully examine their clothing and bodies and promptly remove any
ticks they find.
Diplopoda
Millipedes
[Illustration: Fig. 75.—Diplopoda. _Parajulus impressus_, a common
Illinois millipede. Actual length 1.5 inches.]
[Illustration: Fig. 76.—Chilopoda. _Scutigera forceps_, the house
centipede, commonly found in dark basements. Actual length of body
1.0 inch.]
[Illustration: Fig. 77.—Chilopoda. A common type of woodland
centipede found in leaf mold and rotten logs. Actual length 1.0
inch. (Drawing from R. E. Snodgrass.)]
Elongate animals each having a distinct head and a long, many-segmented
body with two pairs of legs on every segment. The commonest Illinois
representative is the large _Parajulus impressus_ (Say), fig. 75, a
robust, cylindrical, reddish species commonly found in rotten logs or
moist leaf mold. Most species feed on decaying vegetable matter. A few
occasionally do considerable damage in greenhouses.
Chilopoda
Centipedes
Elongate animals, similar in general appearance to the millipedes but
with only one pair of legs on each body segment. Many species are
predacious, feeding on insects and other small animals in rotten logs
and humus. Most familiar to the city dweller is the house centipede,
_Scutigera forceps_ Rafinesque, fig. 76; this is a common inhabitant of
dark places in houses, where it runs about with incredible speed in
search of the small insects upon which it feeds. Other species may be
encountered under boards and stones in gardens, fig. 77. Some Illinois
centipedes found in woody or rocky situations are 2 inches or more long.
No chilopod group in this state is dangerous to human beings, but to the
south occur centipedes nearly a foot long that may inflict serious
bites.
THE STATE INSECT COLLECTION
[Illustration: Fig. 78.—The Natural Resources Building. This
building, on the campus of the University of Illinois, is the home
of the Illinois Natural History Survey and houses the state insect
collection on the second floor of the west wing. (Photograph from
Illinois Geological Survey.)]
Illinois is one of the very few states that maintain a large research
insect collection. This collection is under the care and guidance of the
Section of Faunistic Surveys and Insect Identification of the Illinois
Natural History Survey. It is housed in the west part of the fireproof
Natural Resources Building on the University of Illinois campus at
Urbana, fig. 78. Begun about 1880, the collection has grown steadily
until now it is the most extensive representative collection of the
insect fauna of any state in the nation. The collection consists of over
5,500,000 specimens of insects housed in steel cabinets, fig. 79. The
pinned collection includes about 750,000 specimens in trays. The
collection preserved in alcohol contains over 3,500,000 insects
including not only a great number of valuable adult insects but also a
very useful collection of immature insects. The slide collection
contains nearly 250,000 specimens mounted as permanent microscopic
preparations. The papered and boxed material comprises more than
1,000,000 specimens of dried insects.
[Illustration: Fig. 79.—A view of the main insect collection room of
the Illinois Natural History Survey. In the steel cabinets and
hardwood trays shown here are arranged pinned insect specimens.
Similar cabinets contain material in liquid preservative. Adjoining
this collection room are offices and laboratories of the Section of
Faunistic Surveys and Insect Identification, where records of insect
distribution and habits are kept on file.]
The most important use of the collection is for identification of
insects known to damage crops, stored grains, and household articles, or
to threaten human health. Important also is its use as a storehouse of
information regarding the ecology, host relationships, and distribution
of Illinois insects.
So large is the field of insect classification that many important gaps
exist in our knowledge of the Illinois fauna. For maximum usefulness,
the collection should contain a complete representation of the Illinois
insect fauna, supplemented with as much additional North American
material as can be obtained. This additional comparison material is
frequently necessary to evaluate correctly the species occurring in the
state. It is estimated that there are about 20,000 different species of
insects in Illinois and 150,000 in North America. The collection
contains representatives of over 15,000 Illinois species, and a great
many other North American species useful as comparison material in the
identification of Illinois forms.
Gifts to the collection of well-prepared material are greatly
appreciated. Many of those already received have made vital
contributions to the collection and added valuable records to the
Natural History Survey files of insect distribution.
REPORTS ON ILLINOIS INSECTS
As a result of the accumulation of material and information in the
faunistic collection, the Illinois Natural History Survey has published
a number of reports dealing with various groups of insects and other
animals in Illinois; other reports in this series are being prepared or
planned. These reports are designed primarily for use of the advanced
student in zoology and entomology. They contain information regarding
the characteristics, habits, and distribution of the various species in
the state, keys for their identification, and illustrations to assist in
diagnosis of the structures used in identification. Because of their
great abundance in both species and numbers, and their importance as
pests, insects have been studied extensively and much has been written
about them.
The following reports of Illinois insects and their relatives have been
published by the Illinois Natural History Survey. Those marked “out of
print” are unavailable at the Survey, but may be consulted at libraries
or obtained from book dealers. Interested persons may obtain
publications by writing to the Chief, Illinois Natural History Survey,
Urbana, Illinois 61801.
The Oribatoidea of Illinois [Mites], by Henry E. Ewing. Out of print.
The Chironomidae, or Midges, of Illinois, by J. R. Malloch. Out of
print.
A Preliminary Classification of Diptera, by J. R. Malloch. Out of
print.
The North American Species of the Genus _Tiphia_ [Wasps], by J. R.
Malloch. Out of print.
The Pentatomoidea of Illinois [Stink Bugs], by Charles Arthur Hart.
Out of print.
Forest Insects in Illinois: I. The Subfamily Ochthiphilinae (Diptera,
Family Agromyzidae), by J. R. Malloch. Out of print.
Fall and Winter Stoneflies, or Plecoptera, of Illinois, by Theodore H.
Frison. Out of print.
The Plant Lice, or Aphiidae, of Illinois, by Frederick C. Hottes and
Theodore H. Frison. Out of print.
The Dermaptera and Orthoptera of Illinois, by Morgan Hebard.
The Stoneflies, or Plecoptera, of Illinois, by T. H. Frison.
Nearctic Alder Flies of the Genus _Sialis_ (Megaloptera, Sialidae), by
H. H. Ross. Out of print.
The Plant Bugs, or Miridae, of Illinois, by Harry H. Knight.
Studies of North American Plecoptera, With Special Reference to the
Fauna of Illinois, by T. H. Frison.
The Caddis Flies, or Trichoptera, of Illinois, by Herbert H. Ross. Out
of print.
The Leafhoppers, or Cicadellidae, of Illinois, by D. M. DeLong.
The Pseudoscorpions of Illinois, by C. Clayton Hoff.
The Mayflies, or Ephemeroptera, of Illinois, by B. D. Burks.
A Synopsis of the Mosquitoes of Illinois (Diptera, Culicidae), by
Herbert H. Ross and William R. Horsfall.
USEFUL BOOKS
A considerable number of books can be of great help to the beginner in
naming his specimens. The following are perhaps the most easily used.
Others are being published from time to time.
An Introduction to Entomology, by J. H. Comstock. The Comstock
Publishing Company, Ithaca, N. Y.
The Butterfly Book, by W. J. Holland. Doubleday, Doran & Company,
Garden City, N. Y.
The Moth Book, by W. J. Holland. Doubleday, Page & Company, Garden
City, N. Y. Out of print, but may be obtained from secondhand
book dealers.
How to Know the Insects, by H. E. Jaques. H. E. Jaques, 709 North Main
Street, Mount Pleasant, Iowa.
Insects: A Guide to Familiar American Insects, by Herbert S. Zim and
Clarence Cottam. Simon and Schuster, Inc., Rockefeller Center,
New York 20, N. Y.
Field Book of Ponds and Streams, by Ann Haven Morgan. G. P. Putnam’s
Sons, New York, N. Y.
The Insect Guide, by Ralph B. Swain. Doubleday & Company, Inc., Garden
City, N. Y.
College Entomology, by E. O. Essig. The Macmillan Company, New York,
N. Y.
Entomology for Introductory Courses, by Robert Matheson. The Comstock
Publishing Company, Ithaca, N. Y.
A Textbook of Entomology, 3rd ed., by Herbert H. Ross. John Wiley &
Sons, Inc., 440 Park Avenue South, New York, N. Y.
Understanding Evolution, by Herbert H. Ross. Spectrum Books:
Prentice-Hall, Inc., Englewood Cliffs, N. J. 07632.
HOW TO SHIP SPECIMENS
Specimens which the collector is unable to name may be sent to
specialists or entomological museums for identification. Names and
addresses of specialists can be furnished by agricultural agents,
teachers, or museum curators. The arrangements under which these
specialists will undertake the work vary, but experts often will study
well preserved and labeled collections in return for duplicate specimens
which they may keep. However, the identification of many insects is so
difficult and laborious that rapid service is not always to be expected
by collectors sending in material.
Specimens need special preparation and care to guard against breakage if
they are to be shipped to a specialist.
See that all pins used in mounting specimens are thrust securely into
the cork on the bottom of the box. Thrust extra pins of the same height
in each corner, and over the whole lay a piece of thin cardboard that
has been cut to fit the inside of the box snugly; then place over this a
layer of cotton wool or cellucotton thick enough to press firmly against
the cardboard when the top is closed. Wrap the box in paper and then
pack it in a larger box, protected on all sides by a layer of excelsior
or crumpled paper at least 2 inches thick.
WHERE TO BUY SUPPLIES
The following list, by no means complete, contains names and addresses
of companies that furnish entomological supplies. Most of these
companies will send catalogs and price lists on request.
American Optical Company, Scientific Instrument Division, Box A,
Buffalo 15, N. Y.
Bausch and Lomb Optical Company, Rochester 2, N. Y.
Central Scientific Company, 1700 Irving Park Road, Chicago 13,
Illinois.
General Biological Supply House, Inc., 8200 South Hoyne Avenue,
Chicago 20, Illinois.
E. H. Sargent and Company, 4647 West Foster Avenue, Chicago 30,
Illinois.
Ward’s Natural Science Establishment, Inc., P. O. Box 1749, Rochester
3, N. Y.
[Illustration: Endpapers]
Transcriber’s Notes
—Silently corrected a few typos.
—Retained publication information from the printed edition: this eBook
is public-domain in the country of publication.
—In the text versions only, text in italics is delimited by
_underscores_.
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