666 



TEXT-BOOK OF ENTOMOLOGY 



The bud is differentiated into a central discoidal bud, a furrow, and 

 a marginal, rather thick swelling or pad. Afterwards, these buds 



elongate and form 

 small papilliform pro- 

 jections directed back- 

 wards (Fig. 621) ; but 

 only during the pupal 

 period do they, as 

 already observed in 

 Bombus, approach each 

 other and assume their 

 definite shape as an 

 ovipositor. 



Finally, Bugnion 

 states that while meta- 

 morphosis in the Hy- 

 menoptera is less highly 

 modified than in the 

 Muscidae, it is more 

 marked than in the 

 Coleoptera and Lepid- 

 optera. In these orders 

 the pupa moves the 

 abdomen, but in Hy- 

 menoptera it is abso- 

 lutely immovable 



FIH. 621. The same in an older larva ready to transform : throughout pupal life, 

 i, intestine ; a>, genital gland ; a, anus. After Bugnion. ^g Ion " as the 



meut is soft. 



FIG. 620. End of larva of Encyrtus of 2d stage, showing 

 the three pairs of imaginal buds of the ovipositor q 1 , g 2 , qt. 



DEVELOPMENT OF THE IMAGO IN THE DIPTERA 



The flies, particularly the Muscidse and their allies (Brachycera), 

 are the most highly modified of insects, their larvae having under- 

 gone the greatest amount of reduction and loss of limbs, this 

 atrophy involving even most of the head. The following account 

 has been prepared in part from the works of Weismann, Ganin, 

 Miall, and Pratt, but mostly from the excellent general summarized 

 account given by Korschelt and Heider. 



In the holometabolic orders of insects, with their resting pupal 

 stage, during which no food is taken, the entire activity of life 



