CULICIDJE 



785 



the characters of the leaflets and their terminal hairs, if present. These hairs 

 are of use in helping to keep the larva in its horizontal position when it comes 

 up to breathe on the surface of the water. 



The stigmatic siphon is placed, as already mentioned, on the eighth seg- 

 ment, forming by means of raised, toothed, chitinous processes a quadrilateral 

 space. 



Fig. 389. — Larva of an Anopheline Mosquito lying' Parallel to 



THE Water. 



(Modified after Howard.) 



Fig. 390. — Larva of a Culicine Mosquito hanging down from the 

 Surface of the Water. 



(After Howard.) 



The teeth are of great importance, being capable of being approximated so 

 as to close the cavity, and thus protect the two openings of the tracheae which 

 lie in the anterior portion of the siphon. From these openings the long 

 tracheae can be seen running from back to front along the larva. 



The duration of the larval stage varies with food and tempera- 

 ture, being longer in the temperate zone than in the tropics. 

 According to Stephens, it is twelve days in Cellict argyrotarsis and 



50 



