32 CHILDHOOD OF ANIMALS 



privet and hatch into caterpillars which feed on the leaves. The 

 caterpillar (Fig. i6) has a head and a jointed worm-like body. 

 The head has six simple eyes, a pair of three-jointed very small 

 antennae, and biting jaws. The first three segments of the body 

 carry each a pair of five -jointed clawed legs, corresponding with the 

 legs of the adult insect. Four of the other ten segments carry each 

 pair of larval legs, called prolegs, and not represented in the adult, 

 but entirely for the purposes of the larva. The caterpillar feeds and 

 grows, and moults three or four times. Before the last moult, 

 it becomes restless and wanders about, ceasing to feed. It is ready 



for pupation, and is 

 seeking a suitable 

 place. Some cater- 

 pillars suspend them- 

 selves to the branch 

 of a tree or to a pro- 

 jecting point in a dry 

 crevice. Others spin 

 a cocoon of silk. 

 Others, such as the 

 privet hawk - moth 

 caterpillar, descend to 

 the ground and scoop 

 out a dry burrow. 



Fig. 1 6. Caterpillar (upper figure) and Chrysalid (lower There the last moult 

 figure) of Privet Hawk-moth. (Slightly reduced.) ^^^^^ ^-^^^^^ ^^^ ^^^ 



pupa or chrysalid (Fig. i6) emerges, and very quickly becomes 

 hard and brown. If it be examined closely, however, it can be seen 

 to resemble a moth more than a caterpillar. It shows the shape of the 

 head, body and abdomen of the moth and carries the appendages of 

 a moth, not of a caterpillar, and is provided with short, folded 

 wings. These are at first free, but soon, before the skin has become 

 dry and brown, are glued down with a sticky secretion. The pupa 

 is able to wriggle, but remains practically motionless while the 

 transformation to the adult is taking place. In the course of this 

 there is a suppressed moult, shown by the presence of a very thin 

 skin covering the body of the moth inside the pupa-case, like one of 

 the two skins in the blow-fly, and like these representing an almost 

 forgotten moult. When the moth emerges, it is ready to fly as soon 

 as its wings have expanded and dried, and it is extremely unlike the 

 caterpillar. But the gap is not so great as in the blow-fly. In the 



