THE LARVA 39 



When full ^'own they sometimes stray to a nei,£;hboniing plant 

 or fence to undergo the change to a chrysalis, but more commonly 

 they are perfectly satisfied with the protection afforded by the leaves 

 of their food plant. We will now watch one of these as we did the 

 larva of the Large White Butterfly. 



Of course the under side of the leaf is chosen. Here a silken 

 carpet is spun as before described ; but the caterpillar, instead of 

 clinging with all its claspers, suspends itself in a vertical position 

 by its hindermost pair only. 



Here it hangs, head downwards, awaiting the coming events. 

 The splitting and casting of the skin goes on just as in the case of 

 the Large White, but there is this puzzle to be solved : how 

 can the insect shufHe itself out of its old coat without falling to the 

 ground, leaving the cast-off garments still hanging by the hooks 

 of the claspers ? This really seems a matter of impossibility, since 

 the little hooks which alone suspend the insect are thrown off with 

 the skin of the claspers. 



The thing is managed in this way. As the skin slowly splits 

 through the wrigglings of the apparently' uncomfortable occupant, 

 it is gradually pushed backward — that is, upward — till it is in a 

 shrivelled condition, and the body of the insect is nearly free. But 

 the chrysalis thus brought to light is provided with little hooks on 

 the end of its ' tail ' by which it can attach itself to the irregularities 

 of the crumpled coat. Its conical abdomen is also very flexible, 

 and it can, by bending this, seize hold of a ridge in the skin, 

 holding it between the segments. Thus, although practically quite 

 fi-ee from the old garb, it never falls to the ground. 



There is now, however, another point to be attended to. The 

 newly formed chrysalis desires to be entnely independent of its 

 cast-off skin, and to suspend itself directly from the silky carpet it 

 has prepared. To this end it works steadily for a time, alternately 

 bending its supple abdomen fr'om side to side, gripping the folds of 

 the skin between the segments, pulling its body a little higher at 

 each movement, and securing itself at each step by the little hooks 

 at its extremity. 



So it climbs, and at last it reaches the network of silk fibres, and 

 thrusts the tip of its abdomen among them till some of the hooks 

 have taken hold. Not satisfied with this, it turns its body round 

 and round to get the little hooks so entangled between the silk 

 fibres that a fall is impossible, and in so doing it freijuently pushes 

 the old skin out of its place so that it falls to the ground. 



