MOSQUITOES AND FLIES 



species which unquestionably have gone farthest along 

 the road of mechanical efficiency have produced little else 

 commendable. In this class we would place the mos- 

 quitoes and the flies; and who will say that either mosqui- 

 toes or flies have added anything to the comfort or enjoy- 

 ment ot the other creatures of the world? 



Reviewing briefly the esthetic contributions of the 

 major groups of insects, we find that the grasshoppers 

 have produced a tribe of musicians; the sucking bugs have 

 evolved the cicada; the beetles have given us the scarab, 

 the glow-worm, and the firefly; the moths and butterflies 

 have enriched the world with elegance and beauty; to the 

 order of the wasps we are indebted for the honeybee. 

 But, as for the flies, they have generated only a great 

 multitude of flies, amongst which are included some of 

 our most obnoxious insect pests. 



However, in nature study we do not criticize; we derive 

 our satisfaction from merely knowing things as they are. 

 If our subject is mosquitoes and flies, we look for that 

 which is of interest in the lives and structure of these 

 insects. 



Flies in General 



The mosquitoes and the flies belong to tne same ento- 

 mological order. That which distinguishes them princi- 

 pally as an order of insects is the possession of only one 

 pair of wings (Fig. 167). Entomologists, for this reason, 

 call the mosquitoes and flies and all related insects the 

 Diptera, a word that signifies by its Greek components 

 "two wings." Since nearly all other winged insects have 

 four wings, it is most probable that the ancestors of the 

 winged insects, including the Diptera, had likewise two 

 pairs of wings. The Diptera, therefore, are insects that 

 have become specialized primarily during their evolution 

 by the loss of one pair of wings. 



We shall now proceed to show that the evolution of a 

 two-winged condition from one of four wings has been a 



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