130 



THE SPIMY ELM CATERPILLAR 



About four weeks from the time of hatching these Spiny 

 Elm Caterpillars become full grown. They then leave the 

 tree or shrub on which they have been feeding and scatter 

 about, seeking some sheltered situation. Having found 

 this, — perhaps beneath a stump or along the underside of a 

 fence, — each caterpillar spins a web of silk along the surface. 



It then entangles the 

 hooked claws of its hind 

 legs in this silken web 

 and lets its body hang 

 vertically with the head 

 end curved upward. It 

 remains in this position 

 for some hours before the 

 skin along the back just 

 behind the head splits 

 apart and is gradually 

 wriggled . upward until it 

 is tinally all removed, and 

 there hangs in place of 

 the caterpillar a peculiar 

 object having no definite 

 form. Bnt it rapidly as- 

 sumes a definite form — 

 that of the chrysalis 

 which is represented in 

 Fig. 46. These pictures 

 will show sufficiently the shape and size of the chrysalis, which 

 is of a grayish brown color, different specimens varying some- 

 what in shade. 



In this quiet chrysalis the insect is apparently almost as 

 inert as a mummy. If you touch it, it will wriggle a little 

 but otherwise it hangs there mute and helpless. On the 

 inside, however, the. tissues are being made over in such a 

 wonderful way that in about two weeks, from the mummy- 

 case into which the caterpillar entered, there comes' a^ beauti- 

 ful butterfly. When it first breaks the mummy-shell its wings 



Fig. 40. Four vien-s o£ the clirysaUs. 

 Natural size. 



