8 BRITISH BUTTERFLIES AND MOTHS 



fleshy prolegs, by means of which the larvae have great 

 power of holding on to any substance on which they are 

 resting. These caterpillars feed voraciously, and soon 

 have grown to such an extent that it is necessary to 

 cast off their skins. When the period for this approaches 

 they cease feeding, and seem dull and stupid. They fix 

 themselves firmly by their hind legs, and in a short time 

 the skin behind the head cracks, and the larva gradually 

 wriggles its way out of the opening, and walks off, leav- 

 ing behind it the old empty skin sticking to the leaf. 

 The larva, when thus freshly moulted, is already con- 

 siderably larger than the skin from which it has escaped ; 

 but it is soft and tender, and it has to wait a little time 

 for its new skin to harden ; but when that has happened, 

 it sets to work vigorously, and eats with renewed appe- 

 tite. After spending some days in the happy state of 

 alternately eating and sleeping, it has again to go 

 through the process of casting its skin a process which 

 is repeated four or five times before the larva is full fed. 

 When quite full fed, the larva crawls away from the 

 plant on which it has been feeding, and creeps up a wall 

 or paling till it finds a convenient nook adapted to its 

 purpose ; it then spins a bit of silk very firmly to the 

 wall or paling, and fastens its hind legs in this silk, and 

 then it passes a narrow belt of silk round the middle of 

 its body, making both ends fast to the wall or paling. 

 These silken fastenings are generally so placed that the 

 larva is in a perpendicular position, with its head 

 upwards ; it then curves the anterior portion of its body 

 a little, and rests quietly waiting for the change that is 

 to come over it. In a day or two the skin of the cater- 

 pillar cracks towards the head, and is pushed down 

 inside the belt and towards the tail, whence eventually 



