432 



MOSQUITOES 



using their tracheal gills, but they die within a few hours if 

 shut in water without dissolved air. 



Mosquito larvae, unless suspended from the surface film by 

 means of the breathing tube, have a tendency to sink and they 

 rise again only by an active jerking of the abdomen, using it as 



Fig. 196. A, Larva of tropical house mosquito, Culex quinquefasciatus; ant., 

 antennae; br. t., breathing tube or siphon; m. br., mouth brushes; th., thorax; 

 8th s., 8th abdominal segment; 9th s., 9th abdominal segment; tr., tracheae; 

 tr. g., tracheal gills. S, Larva of Anopheles punctipennis; note absence of breath- 

 ing tube, and starlike groups of scales on abdominal segments; m. br., mouth 

 brushes; br. p., breathing pore; other abbrev. as on Fig. A. X 10. (After 

 Howard, Dyar and Knab.) 



a sculling organ. Some species are habitual bottom feeders, 

 others feed at the surface; some live on microscopic organisms, 

 others on dead organic matter, and still others attack and devour 

 other aquatic animals, including young mosquito larvae of their 

 own and other species. 



The larvse shed their skins four times and then go into the 



