A Guide for the Study of Animals Part 3

a. The b.u.t.terfly or moth.

b. An antenna (feeler).

THE LIVING CATERPILLAR

_Materials._

Living caterpillars in cages or covered jars for individual study, and other specimens in cages with foliage for food or concealment.

_Observations._

The pupil should observe the general form and external construction of the caterpillar, watching it feeding, in action, and at rest.

Notice how the creature moves. Find its head, its segments (similar divisions of the body), and its breathing holes along the sides of the body. Try to find its eyes, any feelers, wings or paddles. Try to loosen it from its support; find the tiny hooks on the feet for clinging fast.

_Questions._

1. Give the general color of your specimen and explain how this color may make it conspicuous or may aid its concealment.

2. Describe the outer surface or covering of the caterpillar. What structures, if any, are there, which might make the animal distasteful or inedible?

3. How many pairs of legs are there? How are they distributed along the body? Counting the segments, state which ones bear no legs.

4. To what extent do the legs act in locomotion? Are they mere organs for attachment while the body swings forward and backward, or do the legs do this, as in a horse? Make a complete statement.

5. Notice the openings of the internal breathing tubes. How are they protected against dust and other foreign matter?

6. Does the caterpillar seem to be a warm-blooded animal? State how the free access of air along the body would influence internal temperature.

7. What do you know about a caterpillar's appet.i.te? How might caterpillars be beneficial or harmful? What means has nature of holding their numbers in check?

8. Recalling that caterpillars finally "sleep" for several days or weeks and awaken as winged creatures, how can you account for their appet.i.tes?

THE TUSSOCK MOTH

_Materials._

Directions for the study of the caterpillar stage will be found in the exercise "The Living Caterpillar," and directions for the study of the adult male form will be found in the exercise "The Living b.u.t.terfly or Moth." The female tussock moth is a wingless, thick-bodied creature, gray in color, very downy, and about three fourths of an inch long. The following directions apply more particularly to the study of the coc.o.o.ns and the general harmfulness of the tussock moth.

This exercise may be done best outside of the cla.s.sroom, the pupil answering the questions on sc.r.a.p paper and rewriting these notes in the laboratory. Living caterpillars, coc.o.o.ns, some of them bearing their frothy ma.s.ses of wax and eggs, pupae, and adult moths of both s.e.xes may be used in the laboratory.

_Observations and Questions._

1. On what kinds of trees are the coc.o.o.ns and the caterpillars generally found? What effect have the caterpillars on the trees, and what may possibly be the final effect upon the trees of the locality or the entire district?

2. Upon what part of the tree are the coc.o.o.ns made, and why? Where on the bark are they, and why?

3. Is the opening of the coc.o.o.n at the upper or the lower end? What reason can you a.s.sign for this?

4. Count the number of coc.o.o.ns upon the entire tree or estimate it by counting those upon a part of the tree. Now count the number of eggs on a coc.o.o.n. a.s.suming that one half of the coc.o.o.ns bear eggs, calculate the number of caterpillars on a tree next year.

5. How is the waxy covering of the eggs a particularly good protection against winter weather?

6. Investigate the interiors of several coc.o.o.ns and state what you find.

7. On the pupa find the jointed and tapering hinder end, abdomen, and at the head region and lying along the under side, the marks of the legs and the feelers, and possibly the wings, all pressed close against the body. Find also the breathing pores along the sides of the abdomen.

8. Unlikeness between male and female is called "s.e.xual dimorphism."

Explain how the tussock moth shows this. For what work does each form seem particularly adapted?

9. What methods would you use that the tussock moth might be destroyed or kept out of a community?

The numerous small worm-like creatures often found are the caterpillar stages of another insect, an ichneumon fly, which laid its eggs under the skin of the tussock caterpillar. How has their development affected that of the tussock moth? What great result does nature accomplish by this arrangement?

_Suggested drawings._

a. A caterpillar, 2.

b. A coc.o.o.n with its egg ma.s.s.

c. A pupa as seen from the under side.

d. An adult moth, either male or female.

THE LIVING BEETLE

_Materials._

Living beetles in cages, together with portions of the plant upon which they are found; or if water beetles are used, they should be kept in aquaria. Individual specimens in battery jars or wide-mouth bottles, and preserved beetles in pans or vials for reference.

_Observations._

1. Upon what plant or in what surroundings is your kind of beetle generally found? If you can, give its common name.

2. What is the length, breadth, and thickness of your beetle? Would you describe it as a "small" insect or a "large" one?

3. Of what general color is it? Describe any color markings you see.