Mosquitoes 



103 



two ounces, is said to make a good repellant and is 

 effective for a long time. 



FIGHTING THE LARVM 



All of the efforts directed against the adult mos- 

 quitoes are usually of little avail in decreasing the 

 number in any region. It is comparatively easy, 

 however, to fight them successfully in the larval 

 stage. We have seen that standing water is abso- 

 lutely necessary for mosquitoes to breed in. This 

 makes the problem much simpler than if they 

 could breed in any moist places such as well- 

 sprinkled lawns, a shady part of the garden, etc. 

 The whole problem of successful campaigns 

 against the mosquitoes resolves itself into the prob- 

 lem of finding and destroying or properly treat- 

 ing their breeding-places. We have seen how cer- 

 tain kinds, such as the yellow fever mosquito, are 

 " domestic " species. They never go far from 

 their breeding-places. If a house is infected by one 

 of these species the immediate premises should be 

 searched for the source. Cisterns, rain-barrels, 

 sewer-traps, cesspools, tubs or buckets of water or 

 old tin cans in out-of-the-way corners, are all suit- 

 able places for them to breed in. Cisterns and rain- 

 barrels should be thoroughly screened so that no 

 mosquitoes can get in or out, or the surface should 



