240 



INTRODUCTION TO ZOOLOGY 



CHAP. 



found, mark the leaf on which they are, and visit daily. Keep a 

 record of their development, noting dates of hatching, first moult, 

 successive moults, time of dispersal of the brood, date of pupation, 

 etc. In order to find the chrysalis with ease, it may be well to 

 cover the plant, when the caterpillars are large, with a tall but light 

 frame covered with muslin. 



2. Bring a few large caterpillars indoors for more detailed study. 

 Examine with a lens, and carefully 

 sketch one of them, making clear all 

 the main points in its external 

 structure. Watch the movements of 

 the jaws as the caterpillar feeds. 



3. Place a full-fed caterpillar in- 

 side a tall glass cylinder. 1 Make 

 the cylinder firm by fixing its lower 

 end in a pot of earth, cover the top 

 with a piece of muslin or perforated 

 zinc, shade one side of the cylinder 

 (Fig. 167). The caterpillar will prob- 

 ably begin at once to climb up the 

 glass, and, when so doing, its struc- 

 ture can be very clearly seen, and 

 also the way in which it secretes 

 silk from the spinning-tube, fixing a 



FIG. 167.-Simple Breeding-cage zi g za g ladder to the g lass ' When 

 for the caterpillars of moths it reaches the top, it will probably 

 or butterflies. stop and fix itself in preparation for 



e, A pot of earth ; c, a glass cylinder ; pupation. Note the time of fixing, 

 d, a pot of wet sand sunk in the watch the formation of the silken 

 irdle which supports the body and 

 rr J I 



in two days' time be on the look-out 

 for the splitting of the skin and the appearance of the chrysalis. 



4. Try the effect of changing the environment of caterpillars 

 when about to pupate. Cover the wall of the breeding cage in 

 one case with gold paper, in another with black or red paper, and 

 note the colour of the chrysalis in each case. 



5. Put the chrysalids into an airy place, and when the time 

 comes (i.e. in two or three weeks if it is the first brood of the year, 

 or the following May if it is the second brood) watch for the emerg- 

 ence of the imago. 



6. Distinguish the male and female butterflies, and draw a speci- 

 men of each. Suspend in the insect cage a small sponge soaked in 

 honey and watch the butterflies feeding on it. Finally set the 



1 The glass cylinders sold as candle screens are very suitable. 



earth, and containing the food- 

 plant, b ; a, muslin cover. 



