72 The Control of Mosquitoes 



grade the more likely are such conditions to occur. 

 The higher the temperature of the water the more 

 favorable it becomes for rapid development. 

 Anopheles larvae have been taken in ditch water 

 having a temperature of 102 degrees Fahrenheit. 



CRAB HOLES AND PLANTS AS SOURCES OF ANOPHELES 



Anopheles larvae have been taken from crab 

 holes both in depressions on fiat land and on river 

 banks which received larvae from receding waters. 

 It is known that Anopheles seldom if ever lay eggs 

 in crab holes where water is below the ground 

 surface. One species of mosquito, which does 

 not bite man, habitually lays its eggs in sub- 

 surface water in crab holes. It is not an A nopheles. 



While larvae of some species are found in water 

 held by stems of plants, and in tree holes, the 

 species that enter dwellings and are known to be 

 malaria carriers seldom oviposit in such places. 

 Propagation in water held by plants and trees was 

 not considered of economic importance on the 

 Isthmus. 



CHANGE OF SPECIES CAUSED BY CHANGES OF SEASON 

 OR OF LOCAL CONDITIONS AT BREEDING PLACES 



It would be natural to expect a prolific source 

 oi Anopheles albimanus, or Anopheles malefactor, to 



