CHAPTER IV 



GNATS 



ALTHOUGH the majority of insects are terrestrial and aerial in 

 their habits, yet there are not a few which pass part or the whole 

 of their lives in water. The 

 system of tracheal tubes by 

 which most insects breathe is 

 obviously suited to life on land. 

 Hence aquatic insects exhibit 

 numerous interesting modifica- 

 tions of structure, in adapta- 

 tion to the special conditions 

 imposed upon them by life in 

 water. 



The most abundant and 

 most easy to rear and observe 

 of all these insects are the 

 gnats, of which there are very 

 many species, from which we 

 select two for the present work 

 namely, Culex and Chiron- 

 omus. The eggs, larvae and 

 pupae of both these forms are 

 to be found in almost any 

 stagnant water, even when 

 occurring in such small quan- 

 tities as may accumulate in 

 old tins, jam pots, etc., to say 

 nothing of exposed water- 

 butts, Cattle-trOUghs and nat- FIG. 9 Imago of male culex. (After Miall.) 



ural sheets of standing water. They can be reared without any 



difficulty in shallow vessels, e.g. saucers, pie-dishes and similar 



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