A Guide for the Study of Animals Part 8

_Reproduction and Development._

19. Describe the ovipositors and the probable method of their use.

Describe the egg packets of gra.s.shoppers, if discovered. About how many eggs in one? (They are sometimes seen against the gla.s.s sides of the vivaria.)

20. If you have young gra.s.shoppers of various ages, arrange a set of them in what seems to you to be the order of their development. How do young gra.s.shoppers differ from adults? What changes take place as they develop? What kind of metamorphosis is this?

Summary of Important Points in the Study of the Gra.s.shopper

1. How many and what distinct regions of the body are there?

2. How many antennae? Compare their length with that of the body.

What other sense organs did you discover?

3. How many legs? For what specially adapted? How?

4. How many wings? What is their resting position? How do the fore wings differ from the hind wings? How do the hind wings fold?

5. To what kind of feeding are they adapted, biting or sucking the food? How many and what sets of mouth parts are there?

6. How is air necessary for respiration obtained?

7. In what various ways are gra.s.shoppers fitted for life in meadows and weed plots?

8. How do they meet winter conditions?

9. What kind of metamorphosis has the gra.s.shopper?

_Drawings suggested._

a. Side view with the legs and wings removed. Label all parts shown in this drawing. (See Definitions on pages 23 and 24 for names of parts.)

b. Face view of the head, showing the simple and compound eyes, the antennae, labrum, and palps.

c. One of the third pair of legs. Label parts.

d. A fore and a hind wing arranged in natural position.

e. A young gra.s.shopper.

3. COMPARATIVE STUDY OF ORTHOPTERA

_Materials._

Mounted specimens of various common species of orthoptera.

_Observations._

1. Where does the insect live? What is its color?

2. What is the size and shape as compared with the gra.s.shopper?

3. What is the length of the antennae as compared with the length of the body?

4. To what kind of locomotion are the legs adapted? How? Are the forelegs specially adapted for grasping?

5. What is the position of the wings when at rest? Are they large or small as compared with the size of the body?

6. Are the ovipositors long or short? (Compare with those of the gra.s.shopper.)

7. Find the group to which the insect belongs and its name by the key in the following section.

4. KEY TO SOME COMMON ORTHOPTERA

A. Groups

============================================================================= LEGS |ANTENNae| OTHER CHARACTERS | GROUPS -----------------+-----------------------------------------+----------------- Similar, fitted | Long | Body flattened, wings folded on | c.o.c.kroaches for running | | dorsal surface of the abdomen | (_Blattidae_) -----------------+-------+---------------------------------+----------------- First pair of | Rather| Prothorax long and slender, | Mantis legs enlarged | long | wings folded on dorsal | (_Mantidae_) for grasping | | surface of abdomen | -----------------+-------+---------------------------------+----------------- Similar, fitted | | Body usually greatly elongated | Walking stick for walking | Long | and stick-like, usually no | (_Phasmidae_) | | wings | -----------------+-------+---------------------------------+----------------- Hind legs fitted | | Body somewhat compressed, | Short-horned for jumping | Short | wings folded on side of | gra.s.shoppers | | abdomen | (_Acrididae_) |-------+---------------------------------+----------------- | | Body compressed, wings folded | Long-horned | Long | on sides, tarsus four-jointed | gra.s.shoppers | | | (_Locustidae_) |-------+---------------------------------+----------------- | | Body somewhat flattened, wings | Crickets | Long | folded on the back, tarsus | (_Gryllidae_) | | three-jointed | =============================================================================

B. Species or Genera

============================================================================ CHARACTERS OF SPECIES | COMMON NAME | GROUPS -------------------------------------+----------------------+--------------- Large size, brown color | American c.o.c.kroach | Small size, pale brown | "Croton bug" | c.o.c.kroaches Dark color, often wingless | Oriental c.o.c.kroach | -------------------------------------+----------------------+--------------- Body long, anterior portion slender | Mantis or rear horse | Mantis -------------------------------------+----------------------+--------------- Long body, long legs, no wings | Walking stick | Walking sticks -------------------------------------+----------------------+--------------- Very large size, wings very small | Lubber gra.s.shopper | Small to medium size, legs marked | Red-legged | with red | gra.s.shopper | Short-horned Large size, greenish brown color | Differential locust | gra.s.shoppers Medium to large size, sand color | Carolina locusts | (gray) | | -------------------------------------+----------------------+--------------- Rather large, green, wings large | Angle-wing katydid | and angled | | Long-horned Small to rather large, usually green | Meadow gra.s.shopper | gra.s.shoppers Wingless, brown color | Cricket gra.s.shopper | -------------------------------------+----------------------+--------------- Usually rather large, black | Field cricket | Crickets Wingless, front legs shovel-shaped | Mole cricket | ============================================================================

5. THE DRAGON FLY

_An Insect adapted to Aerial Life_

_Materials._

Mounted specimens of dragon flies, some moist preserved specimens, living specimens if practicable, simple lenses.

_Observations._

1. Identify the three regions of the body and note the presence of a distinct neck. What is the length of the insect? What is its general form? If you have living specimens, discover what movements the head and abdomen are capable of making.

2. What is the position and general character of the wings? Explain how these wings are made very efficient for flying. Why should they not fold?