A Guide for the Study of Animals Part 56

_Observations._

1. State the color and appearance of the larva. If tubercles or spines are present, state where. Where are the spiracles? How do you distinguish the head, thorax, and abdomen in the case of the caterpillar?

2. What kind of mouth parts has the caterpillar?

3. How many prolegs has the caterpillar? Of what use are they?

How does the number of prolegs differ from that of the caterpillar in the case of the grub? maggot? currant worm?

4. What is the advantage of the coc.o.o.n? What is its color, appearance, and material? Is it composed of a tough substance, or is it easily torn? Where are coc.o.o.ns found out of doors? Where would you look for chrysalids? (Explain differences in locations.)

Describe the coc.o.o.ns of tussock moth, clothes moth, leaf roller.

5. What is the difference between a Cecropia coc.o.o.n which contains a living pupa and one that has been parasitized? What is the appearance of a parasitized caterpillar?

6. What rudimentary structures can you identify in the pupa? What kind of mouth parts has this stage?

7. Which of these stages is the active stage? Which stage is quiescent? What is really going on in the quiescent stage? In which stage does the insect grow? feed? If the insect were harmful, in which stage would it do the damage? How?

8. Describe what occurs when the pupa changes into the adult. What is the appearance of the wings in the beginning? What changes take place?

9. What kind of mouth parts has the adult? Describe.

10. Describe the antennae.

How do the antennae of moths and b.u.t.terflies vary?

11. What is the size and appearance of the eggs? Are they laid singly or in groups?

_Suggested drawings._

a. A caterpillar, side view.

b. A pupa, ventral view.

c. An adult, dorsal view.

d. A few eggs.

5. Development of the Chick

_Materials._

An incubator, a brooder, a setting of eggs.

_Directions._

Read carefully the directions for setting up and regulating the incubator. Remember that the temperature should average 103 degrees and should not vary more than two or three degrees above or below this. Candle the eggs from time to time and note difference in appearance, as development proceeds, especially as to transparency and size of the air s.p.a.ce. An egg that is transparent after ten days is probably infertile and should be removed. Eggs which are developing properly will show from this time on a well developed air s.p.a.ce, and will be quite opaque. The veins often give a spider-web appearance.

Twice each day remove the tray of eggs and allow to cool slightly.

Once a day the eggs should be turned before the tray is returned to the incubator.

_Questions._

1. Describe the appearance of the sh.e.l.l when the chick is about to come out. In about how many days after you put the eggs in the incubator did you first note this change? You should watch the incubator carefully from the eighteenth day on.

2. What proportion of the eggs hatched? What reasons can you suggest for the failure of some to hatch? Did any which were pipped fail to hatch? If so, break them open and see if you can discover the trouble.

3. How does the chick get out of the sh.e.l.l? How long does it take for it to get out after the sh.e.l.l is chipped? How does a chick look as soon as it has come out of the sh.e.l.l?

4. With what is a chick covered when it is first hatched? How long before feathers begin to develop?

5. How long before a chick needs food? How does it recognize it?

_Summary._

1. What are the two kinds of development?

2. What are the stages in embryonic development?

3. What two general types of postembryonic development as determined by the amount of the food supplied in the egg?

#C. PROTECTION AND CARE OF YOUNG#

Library Exercise

_Materials._

Books and diagrams showing as many methods for the care of young as possible.

_Observations._

1. To what extent is care given to the eggs and young in the case of fish? Is the number of eggs large or small? Contrast this condition with that of the robin. What general conclusion is suggested?

2. Describe the egg-laying habits of five or more of the following: gra.s.shopper, cecropia moth, tussock moth, leaf miner, case bearer, leaf roller, sphinx moth, gall insects, ichneumon flies, spiders, earthworm. How is the developing animal protected in each case? How is food a.s.sured?

3. Contrast the method of the honeybee and the solitary wasp as to the method of caring for and feeding the young.