432 



MOSQUITOES 



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

 shut in water without dissolved air. 



Mosquito larva?, unless suspended from the surface film by- 

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

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



Fig. 19G. A, Larva of tropical house mosquito, Culex quinquefasciatus; ant., 

 antennae; l)r. t., l^rcathing tube or siphon; m. l)r., mouth })rushes; th., thorax; 

 8th s., 8th abdominal segment; 9th s., 9th abdominal segment; tr., trachea^; 

 tr. g., tracheal gills. B, Larva of Anopheles punclipennis; note absence of breath- 

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

 brushes; br. p., lireathing 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 larva? of their 

 own and other species. 



The larva? shed their skins four times and tiien go into the 



