262 



SYSTEMATIC ZOOLOGY. 



molt by which the appearance is greatly changed and 

 the pupal stage is reached. In the pupa (fig. 81) the 

 abdominal legs are lost, the body is shortened and covered 

 with a harder skin, in which one can trace the legs, an- 

 tennas, and wings of the future moth or butterfly, folded 

 over the breast. Many caterpillars of the moths, as a 

 preparation for pupation, spin silken nests or cocoons, 

 the silk being the product of glands which empty into the 

 mouth. The pupa? of butterflies have usually no such 

 silken protection, but are free. From the fact that many 



FIG. 80. Army-worm, larva of Leu- 

 cania unipuncta, showing five (pairs 

 of) abdominal legs. 



FIG. 81. Pupa of a Bombycid moth- 

 a, antenna; I, first pair of legs; w, 

 wings. 



of these butterfly pupaB are marked with patches and 

 spots of gold, they are frequently called chrysalides (sing. 

 chrysalis) . 



The pupal stage lasts for some time (months), during 

 which no food is taken and no motion possible except of 

 the abdominal rings; then the pupal skin is molted and 

 the perfect insect (imago) (fig. 82) emerges. In those spe- 



