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under, revolving their brushes 

 briskly; but they never remain 

 very long below the surface-, as it is 

 necessary for them to take in fresh 

 air often. 



The pupa has the head and 

 thoracic segments much enlarged, 

 making it all "head and shoulders" 

 with a quite insignificant 

 body attached. Upon the 

 thorax arc two breathing 

 tubes, which look like two 

 ears, and therefore when 

 the pupa rests at the sur- 

 face of the water, it remains 

 head up so that these tubes 

 may take in I lie air; at the 

 end of the body arc two 

 swimming organs which are little, 

 leaf-like projections. At thisst;i"< 

 the insect is getting ready to live 

 its life in the air, and for I his reason 

 probably, the pupa rests for long 

 periods at the surface of tin- 

 water and does not swim about 

 much, unless disturbed. How- 

 ever, it is a very strange habit 

 for a pupa to move about, at all. 

 In the case of other Hies, butterflies, 

 and moths, the pupa stage is quiet . 



When fully mature, the pupa 

 rises to the surface of the water, 

 the skeleton skin breaks open 

 down its back and the- mosquito 

 carefully works itself out, until 

 its wings are free and dry, mean 

 while resting upon the float ing 

 pupa skin. This is indeed a frail 

 bark, and if the slightest bree/.e 

 ruffles the water, the insect is 

 likely to drown before its wings 

 are hard enough for (light. 



The reason that kerosene oil, 

 put upon the surface of the water 

 where mosquitoes breed, kills the 

 insects is because both the larvae 

 and pupae of mosquitoes arc- 

 obliged to rise to the surface, and push their breathing lubes through 

 the surface film so that they will open to the air; a coating of oil on the 

 water prevents this, and they are suffocated. Also when the mosquito 

 emerges from the pupa skin, if it is even touched by the oil, it is unable 

 to fly and soon dies. 



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