492 



ARTHROPODA. 



FIG. 530. Musca, house fly (orig.). 



the Hymenoptera, sharply marked off from head and abdomen, its 

 somites being frequently fused. The development is holometab- 

 olous, two kinds of larvae and pupae occurring 

 in its course. The larvae are always apodal, but 

 have either a distinct head with biting mouth 

 parts or they are headless and have a rudimen- 

 tary sucking apparatus (fig. 531). The pupae 

 are correspondingly either free with powers of 

 motion, or are pupae coarctatae (p. 474). De- 

 velopment thus affords characters of systematic 

 importance, and these are supplemented by dif- 

 ferences in length of legs, antennae, haustellum, 

 FIG. 531. -Larva of and in body form. In number of species the 

 : Diptera stand next to the Coleoptera; in num- 



ber of individuals they far exceed them. 

 Sub Order I. NEMOCERA. Elongate with long, many-jointed antenna', 

 long proboscis, long legs. The larvae live in damp'places or in water, where, 

 lacking legs, they swim by movements of the body. The pupae can also 

 swim well. Best known are the innocuous crane flies (TIPULID^E) and the 

 mosquitos (CuLiciD^E) with their numerous species affecting man, among 

 them the forms which carry yellow fever, and Anopheles,* which distribute 

 malaria. The CECIDOMYID^E include the injurious Hessian fly, Cecidomyia 

 destructor* and the paedogenetic Miastor (fig. 498). 



Sub Order II. TANYSTOMA. Resemble the Muscariae (with which 





