A Guide for the Study of Animals

by Worrallo Whitney; Frederic Colby Lucas; Harold Brough Shinn; Mabel Elizabeth Smallwood

Summary of Important Points from the Table

1. What characters are common to all the insects described in the table?
2. What are the various types of wings? Why do they vary?
3. What are the various types of legs? How are they characterized?
4. What are the various types of mouth parts?
5. Show how the variations in insects are related to the habitat and mode of life of the insect.

9. KEY TO THE PRINCIPAL ORDERS OF INSECTS

A1	Insects with no wings. (See [list below].)
A2	Insects with wings	B
B1	With two pairs of wings. (See [Note 1] below.)	C
B2	With one pair of wings		Diptera
C1	Both pairs of wings alike in structure, either membranous or scaly	D
C2	Fore and hind wings unlike in texture, fore wingsfold over hind wings	E
D1	Both pairs of wings membranous, not covered withscales	F
D2	Both pairs of wings covered with scales; mouthparts tubular for sucking		Lepidoptera
E1	Fore wings very smooth, sheath or shell-like, meetingin a straight line when folded; legsadapted for walking, running, or swimming;mouth parts for biting		Coleoptera
E2	Wings not as in E1	I
F1	Wings membranous, usually folded or partlyfolded; few nerves	G
F2	Both pairs of membranous wings usually outspread,many nerves; mouth parts for biting	H
G1	Wings membranous, hooked together and partlyfolded, or outspread, few nerves in the wings;mouth parts for both biting and sucking; regionsof the body usually very distinct		Hymenoptera
G2	Wings membranous, usually folded, few nerves;mouth parts, a beak for sucking and piercing		Hemiptera
H1	Outspread membranous wings, nearly equal insize; antennæ very short and inconspicuous		Odonata
H2	As in F2, but antennæ not short; wings sometimesfolded		Neuroptera
H3	Both pairs of wings membranous, folded abovethe back; fore wings much larger than hindwings; ovipositors long; mouth parts rudimentary		Ephemerida
I1	Fore wings folded over hind wings, crossing attheir tips, which are membranous, base ofwings thickened, mouth parts a beak forpiercing		Hemiptera
I2	Fore wings leathery, folding either at side of bodyor on the back; mouth parts for biting, legsoften adapted for jumping		Orthoptera

Note 1.—When wings are folded, it will be helpful to remember that thickened fore or cover wings always have membranous wings folded beneath them.

	Insects with no wings	Order
a.	Body long and slender, stick-like; legs for walking. Walking stick	Orthoptera
b.	Grasshopper-like. Cricket grasshopper	Orthoptera
c.	Small size; regions very distinct; abdomen spindle-shape. Ants	Hymenoptera
d.	Small size; ant-like in appearance; pale white. White ants	Isoptera
e.	Flattened body, small size; no compound eyes. Springtails and fish moths	Thysanura

10. SUMMARY OF THE STUDIES OF INSECTS

The Effect of Great Numbers

1. Take some insect for illustration, as the house fly, mosquito, tussock moth, or aphis, and show how insects increase in numbers with great rapidity.
2. What can be said about the number of species of insects?
3. There is said to be great competition among insects. Why? For what?
4. How is the great increase of insects held in check by natural means?
5. What are the various habitats of insects? Give as many as you can with examples of insects that use the habitat.
6. Give examples to show how greatly the food of insects and the method of obtaining it varies.
7. Give some illustrations of the great muscular development of insects. Why is this needed?
8. In what various ways are insects protected against their enemies? Give examples to illustrate your statement.
9. Show how and why the great numbers of insects have affected the structure and mode of life of the insects.