Aquatic Insects 115 



direct from the stems of certain water 

 plants, which it pierces with an especially 

 contrived siphon. The food taken by 

 the larvae consists usually of various 

 minute algae, although there are a few 

 forms known to be carnivorous. The 

 small particles of food are wafted into 

 the mouth by the aid of two thick tufts 

 of hair situated on each side of the head. 

 The complete life-history is gone through 

 in a very short time, varying from ten 

 to twenty days according to species and 

 circumstances. One of the factors that 

 have made mosquitoes such a menace 

 to man is that the larvae do not neces- 

 sarily require a large sheet of water in 

 which to live. The larvae of the dreaded 

 mosquito (Aedes argenteus) that acts as 

 the carrier of yellow fever occur in any 

 small quantity of water, holes in tree 

 trunks, old tins, broken jars, etc., fre- 

 quently being selected. 



There is a small and harmless gnat 



