

'47 



Coleoptera and <thcr>, in whi( h the .I|>|M-II<; I |g 



hut t his distini tion cannot always be drawn sharply, hiptera \>i 



aU<> tin- COarctatt type <>(' pup which the pup;! remain- 



enclosed in the old larva! >kin. or pn /xirinm. 



I'll pal characters, though doubtli idaptive and plr. 



mil* am v. have re< rived hut lit 1 !< at tent ion. Lepidnpterou> pn pa- 

 nt many pu/./.liiiLj charactei \amplc. an eye like Mructure 



-resting an ancestral a< tive condition, su< h as -till occurs 

 heterome^aboloua in>e 



FIG. 215. Obtect 

 pupa of milkweed but- 

 terfly, Anosia ple.vip- 

 pus, natural size. 



FIG. 216. Hea-d 

 of chrysalis of Pa- 

 pilio polyxenes, to 

 show eye-like struc- 

 ture. Enlarged. 



Pupation of a Caterpillar. The process of pupation in a caterpillar 

 has been carefully observed by Riley. The caterpillar of the milkweed 

 butterfly (PI. I, A) spins a mass of silk in which it entangles its suranal 

 plate and anal prolegs and then hangs downward, bending up the ante- 

 rior part of the body (B) , which gradually becomes swollen. The skin of 

 the caterpillar splits dorsally from the head backward, and is worked 

 hack toward the tail (C and D) by the contortions of the larva. 



The way in which the pupa becomes attached to its silken support 

 is rather complex. Briefly, while the larval skin still retains its hold on 

 the support, the posterior end of the pupa is withdrawn from the old 

 integument while the latter is being temporarily gripped between two 

 of the abdominal segments of the pupa, and by the vigorous whirling 

 and twisting of the body the hooks of the terminal cremaster of the pupa 

 are entangled in the silken support. At first the pupa is elongate (E) 

 and soft, but.in an hour or so it has contracted, hardened, and assumed 

 its characteristic form and coloration (F). 



Pupal Respiration. Except under special conditions, pupa) breathe 

 by means of ordinary abdominal spiracles. Aquatic pupuj have special 



