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ELEMENTARY ZOOLOGY 



change to the adult mosquito the pupa (which, unlike the 

 wriggler, is lighter than water) floats at the surface of the 

 water, back uppermost. The chitinous cuticle splits 

 along the back and the delicate mosquito comes out, rests 



FIG. 68. The house-flea, Pulex irritans; a, larva; , pupa; t, adult. 

 (The fleas are probably more nearly related to the Diptera than to any 

 other order of insects. (After Beneden.) 



on the floating pupal skin until its wings are dry, and 

 then flies away. Only the female mosquitoes suck blood. 

 If they cannot find animals, mosquitoes live on the juices 

 of plants. They are world-wide in their distribution, 

 being serious pests even in Arctic regions, where they are 

 often intolerably numerous and greedy. Recent investi- 

 gations have shown that the germs which cause malaria 

 in man live also in the bodies of mosquitoes, and are in- 

 troduced into the blood of human beings by the biting 



