THE MOSQUITO'S ENEMIES 37 



must return periodically to a suitable water collec- 

 tion to lay her eggs, and to find another male. The 

 larva spends twelve days in the water. If the mos- 

 quitos in a town are to be reduced it is obvious that 

 this is the time to attack them when they are in 

 the water and can be easily reached. It is very 

 difficult to try to catch and destroy the flying insects, 

 and it is rarely necessary except in sudden outbreaks 

 of yellow fever. Flying mosquitos can be dealt with 

 by fumigation, and the yellow-fever patients must be 

 screened during the early days of illness ; but these 

 are special measures to be undertaken against this 

 disease. 



Flying mosquitos have certain natural enemies like 

 the larvae, but they are rarely efficacious in reducing 

 the numbers of the insects. The chief of these are 

 birds, bats, and lizards. Cold also kills numbers of 

 imagines, while some of the females hide in dark 

 corners and warm rooms, and hibernate throughout 

 the winter. The best and the cheapest method of 

 reducing domestic mosquitos in a town undoubtedly 

 is to destroy them when they are larvae swimming in 

 the water. 



