Forms of Pupae 



119 



But although the limbs are incapable of motion, 

 certain abdominal segments remain free, so that the 

 hind-body can be, to some extent, bent and turned 

 about. And by means of rows of spines on the 

 abdominal segments, the pupa is, in many cases, enabled 

 to work its way out of its shelter when the time for 

 the final change has 

 arrived. In pupce with 

 this habit, the fusion 

 of the appendages 

 with the body is less 

 perfect than in those 

 which never move at 

 all ; consequently they 

 are often distin- 

 guished as incom- 

 pletely obtect, or 

 "incomplete" pupae 



(76, 77). 



Protection for 

 Pupae. — Insects 

 which pass through a 

 pupal stage are neces- 

 sarily in a very 

 defenceless condition, 

 and consequently 

 require some kind of 

 protection. The most 

 usual covering for a 

 pupa is a silken cocoon 

 which is spun by the larva as its last act before 

 passing into the pupal state (fig. 78). The cocoon 

 is formed of silken threads which are produced by 

 the hardening of the fluid secreted by the long, 

 paired tubular spinning-glands. In some cases the 

 cocoon is simply the lining of an earthen cell, the 



Fig. 77. — Pupa of Gipsy Moth (Ocneria 

 dispar.) between leaves, joined by silken 

 threads. (Below to the left is the cast 

 larval skin). From Riley (after Ratze- 

 burg), Insect Life, vol. 2 (U.S. Dept. Agr.). 



