THE DIPTERA 



305 



Family Culicidae (The Mosquitoes). — These are small insects, famil- 

 iar to everyone as they attack man and other animals, and in most 

 species the females feed upon blood. A few species appear to consume 

 plant juices. The mouth parts of the males are much reduced and the 

 members of this sex rarely, if ever, feed. There are many kinds of 

 mosquitoes but the larva) of all live in water and generally not in large 

 ponds but in more or less stagnant water, and the most abundant species 

 develop in temporary pools. 



The adults have scales fringing their wings and also along the veins. 

 The antennae of the males are plumose (feather-like) and very noticeable. 

 The winter is passed either as the 

 egg, larva or adult, according to 

 the species concerned. 



The eggs may be laid either 

 singly, in small clusters, or in 

 masses often called "rafts" on the 

 surface of standing water or even 

 on the ground, hatching in the 

 latter case after rains or the melt- 

 ing of the snow in spring. The 

 number of eggs laid by one insect 

 varies in different species but 

 probably averages several hundred. 



The larvse or "wigglers" live 

 in water and move with a motion 

 which has given them their com- 

 mon name. The head and thorax 

 are large and distinct, while the 

 abdomen is slender, and projecting 

 from next to the last segment of 

 this section of the body is a re- 

 spiratory tube which is usually 



rather long and near the end of which the breathing organs open by 

 a sort of spiracle. When air is desired, the larva floats to the surface 

 and projects the tip of the respiratory tube just above the water level, 

 to renew its supply (Fig. 321). 



The larvse have mouth parts of the chewing type, and some are plant 

 feeders. Most of them, however, are predaceous, feeding on tiny water 

 animals and even on other mosquito larvse, a pair of small brushes 

 at the mouth being used to cause currents in the water and bring food 

 within their reach. They molt four times and, after a varying length 

 of time (a week or 10 days in many cases) in different species and at 

 different seasons of the year, transform into pupae. These are quite 

 different in appearance from the larvse, the head and thorax forming a 



20 



Fig. 321. — Breathing position of larva 

 of Culex (below), and feeding and breath- 

 ing position of Anopheles (above). Much 

 enlarged. (Modified from U. S. D. A. Div. 

 Ent. Bull. 25, n. s.) 



