A Guide for the Study of Animals Part 11

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 PRINc.i.p.aL ORDERS OF INSECTS

A^1 Insects with _no_ wings. (See list below.)

A^2 Insects with wings B

B^1 With _two_ pairs of wings. (See Note 1 below.) C

B^2 With _one_ pair of wings Diptera

C^1 Both pairs of wings _alike_ in structure, either membranous or scaly D

C^2 Fore and hind wings _unlike_ in texture, fore wings fold over hind wings E

D^1 Both pairs of wings _membranous_, not covered with scales F

D^2 Both pairs of wings covered with _scales_; mouth parts tubular for sucking Lepidoptera

E^1 Fore wings very _smooth_, sheath or sh.e.l.l-like, meeting in a _straight line_ when folded; legs adapted for walking, running, or swimming; mouth parts for biting Coleoptera

E^2 Wings not as in E^1 I

F^1 Wings membranous, usually folded or partly folded; _few nerves_ G

F^2 Both pairs of membranous wings usually _outspread_, _many nerves_; mouth parts for biting H

G^1 Wings membranous, hooked together and partly folded, or outspread, _few nerves_ in the wings; mouth parts for _both biting and sucking_; regions of the body usually very distinct Hymenoptera

G^2 Wings membranous, usually folded, _few nerves_; _mouth parts_, a _beak_ for sucking and piercing Hemiptera

H^1 _Outspread membranous_ wings, nearly equal in size; _antennae very short_ and inconspicuous Odonata

H^2 As in F^2, but _antennae not short_; wings sometimes folded Neuroptera

H^3 Both pairs of wings membranous, folded above the back; fore wings much larger than hind wings; ovipositors long; mouth parts rudimentary Ephemerida

I^1 Fore wings folded over hind wings, _crossing_ at their tips, which are membranous, base of wings thickened, mouth parts a beak for piercing Hemiptera

I^2 _Fore wings leathery_, folding either at side of body or on the back; mouth parts for biting, legs often 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. Gra.s.shopper-like. Cricket gra.s.shopper 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 ill.u.s.tration, 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 compet.i.tion 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 ill.u.s.trations 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 ill.u.s.trate your statement.

9. Show how and why the great numbers of insects have affected the structure and mode of life of the insects.

Cla.s.sification

1. By means of ill.u.s.trations from your studies of insects show how cla.s.sification is based upon likeness of structure.

2. In the same manner show how differences in structure affect cla.s.sification.

3. Show how variation in the wings and mouth parts is used to separate insects into orders.

4. What are the principles of cla.s.sification?