8o 



Pupa Stage of Insects. 



in use. Inside the pupa skin great changes are in progress, 

 for either by modifying the larval organs or developing 

 parts entirely new by use of the accumulated material 

 stored by the larva during its prolonged banquet, the won- 



FiG. 24. 





[mm. 



vOSP^l 



Development of the Bee, after Duncan, 



a b Eggs. g Pupa. 



c d ef Larvae. k Caps. 



/ Queen cell. 



derful transformation from the sluggish, worm-like larva, 

 to the active, bird-like imago is accomplished. Sometimes 

 the pupa is surrounded by a silken cocoon, either thick, as 

 the cocoon of some moths, or thin and incomplete as. the 

 cocoon of bees. These cocoons are spun by the larvae as 

 their last toil before assuming the restful pupa state. The 

 length of time in the pupa-stage varies from a few days to 

 as many months. Sometimes insects which are two-brooded 

 remain as pupte but a few daj's in summer, while in winter 

 they are months passing the quiescent peiiod. Our cabbage- 

 butterfly illustrates this peculiarity. Others, like the Hes- 

 sian-fly and codling moth, remain through the long, cold 

 months as larvffi. How wonderful is this! The first brood 



