MOSQUITOES AND FLIES 



the last segment, in which the posterior spiracles (PSp) 

 are located. The larva floats in a horizontal position just 

 below the surface film of the water (Fig. 1 8 1 A), from 

 which it is suspended by a series of floats (Fig. 178 B, e) 

 consisting of starlike groups of short hairs arranged in 

 pairs along the back. The spreading tips of the hairs pro- 



A 



Fig. 181. Feeding positions of Anopheles and Culex mosquito larvae 

 A, Anopheles larva suspended horizontally beneath the surface film, and feeding 

 at the surface with its head inverted. B, Culex larva hanging from the respira- 

 tory tube 



ject slightly above the water surface and keep the larva 

 afloat. In the floating position, the respiratory disc 

 breaks through the surface film, and its raised edges leave 

 a dry area surrounding the spiracles. The long hairs that 

 project from the sides of the thorax and the first three 

 body segments are mostly branched and plumose. 



The Anopheles larva (Fig. 181 A) feeds habitually at 

 the top of the water. When disturbed it shoots rapidly 

 across the surface in any direction, but goes downward 

 reluctantly. In order to feed in its horizontal position, 

 it turns its head completely upside down and with its 

 mouth brushes creates a surface current toward its mouth. 



The pupa of Anopheles (Fig. 179 B) is not essentially 



[34i] 



