428 ENTOMOLOGICAL SOCIETY 



What is true of the parasitic Hymenoptera applies with almost 

 equal force to most of the parasitic Diptera which belong to the 

 same second category, viz, the Tachinidas, the Conopidae, and the 

 parasitic Sarcophagidas. With the GEstridas and the partially 

 parasitic families Nemestrinidae and Bombyliidae the parasitism is 

 likewise confined to the larva, which, however, has become more 

 specialized rather than more degraded. In the CEstridae, as 

 already indicated, the chitinous spines are abnormally developed 

 so as to aid the larva to maintain its position within the body of 

 its host or to pass from point to point ; while in such forms as 

 have access to the air the anal stigmata are well developed. I'n the 

 imagos, the modification is chiefly in the ovipositor of the female, 

 while the eggs have undergone changes similar to those of the 

 insects of the first category and fitting them for being fastened to 

 hair. In the bee-fly larva the first stage reminds us, so far as we 

 yet know it, of that of the blister-beetles in the peculiar post- 

 embryonic modifications which fit it for an active and migrating 

 life. 



With the Hippoboscidae we have still greater modification in 

 larval habit, in that the larva state is passed within the body of 

 the adult female. Here, however, the modifications are greatest 

 in the adult, which is the parasitic state, and they are somewhat 

 similar to those which we find in the Mallophaga another force 

 ful indication of the dynamic influence of environment, and of 

 similar modification following similar habit in widely different 

 groups. The body is peculiarly flattened, the walls thick and 

 horny, the wings small or wanting, and the feet fitted for attach 

 ment to the host. 



In the few parasitic Cecidomyidae there is no noticeable modi 

 fication due to the parasitic habit a fact probably due to its very 

 recent assumption. 



In the Coleoptera the structural modifications are so evidently 

 adaptations to the peculiar form of parasitic life which they pos 

 sess that I need not go into detail before the members of this So 

 ciety. In the Meloidas they have chiefly affected the larva, which 

 is the parasitic form, while the adult, which is non-parasitic, shows 

 little modification as compared with other allied non-parasitic 

 genera. Nevertheless, in some of the genera, as Sitaris and 

 Hornia, the structural modifications which the imago does ex- 



