AQUATIC INSECTS 



mon names, "punkies, " "sand-flies," or others according to 

 the locality. They have very robust legs, and the thorax 

 is low, not humping up above the head. 



As in Chironomus, larvse and pupae are both aquatic. The 

 larvae, swim with a snake-like motion, are whitish, slender 

 and i2-segmented, with delicate, white blood-gills which can 

 be retracted into the hind end of the body (Fig. 229). 



Mosquitoes, Family Culicidae. — Compared with related 

 groups of flies this is a small family including only about a 

 thousand species. However, it is an important one because of 

 the trouble it makes. The habits of mosquitoes have made 

 them familiar to everybody and much study has been devot- 

 ed to them because of the association of certain species with 

 malaria and yellow fever. 



Some species of mosquitoes attack man and other mam- 

 mals, a few attack birds only and many species do not suck 

 blood at all. It is only the females which bite or suck blood; 

 the males live on fruit and plant juices. The males can be 

 recognized by their plumose antennas. One of the most 

 characteristic things about mosquitoes is the structure of their 

 wings, which have a thick fringe of opalescent hairs and 

 scales along their margins and on the veins (Fig. 227). 



Larvae. — Although they live in the water, all mosquito larvag 

 breathe air and are commonly known as wrigglers because 

 of their swimming motions (Fig. 34). In ail of them the head 

 and thorax are large; the abdomen is slender with openings 

 of air-tubes at the tr?-il end. Mosquito larvse are continually 

 wriggling back and forth from surface to bottom where they 

 feed on minute plant and animal cells and on submerged 

 plants; a few are predacious (Fig. 230). 



Pupae. — A mosquito pupa is shaped like a question mark; 

 the air-tubes open from its thorax, comparable in position 

 to the top of the question mark. Mosquito larvae lie parallel 

 to the surface film or hang tails up but the pupas hang with 

 their backs up (Fig. 232). 



293 ' 



