32 HOW INSECTS ARE CLASSIFIED 
the tissues and assisting in bringing on a generous flow of blood, which 
the latter conveys to the insect’s pharynx. In the female mosquito 
similar structures are found, sharp stylets penetrating the flesh and the 
pharynx pumping the blood up through a sucking tube. 
The antenne are of various shapes, from the elaborately feathered 
structures of the male mosquito to the short, peculiar form, orna- 
mented with a prominent bristle, found in many of the so-called 
“ flies.” 
Classification within the order is complex, and is based partly on the 
manner in which the pupal 
skin is ruptured when the 
adult emerges, partly on 
the type of antenna, partly 
on the arrangement of the 
veins in the wings, as well 
as other structural pecul- 
jarities. 
More than 40,000 species 
have been described. 
The number of families 
is very large, but among 
the more important groups 
may be mentioned the 
following : 
Culicide, the mosqui- 
Fic. 31.— Adult mosquito. Enlarged and 
natural size. Original. 
toes. A nuisance to man 
and domestic animals, and in some cases carriers of disease. Larve 
aquatic, as a rule. 
Chironomide, the midges (but not the so-called midges attacking 
wheat, clover, and the like). Larve often aquatic. 
Cecidomyiidie, the gall midges. Many injurious species, some of 
prime importance, as the Hessian fly. 
Simulide, the black flies. Attack man and domestic animals. 
Tabanids, the horseflies. 
Asilidz, the robber flies. Predaceous on other insects. 
