PROPHYLAXIS IN MALARIA 245 



The knowledge of the habits and breeding places of the 

 dangerous species in each place will determine the 

 practicability of dealing with malaria by the extermina- 

 tion or diminution of these definitive hosts. 



With large stations the most satisfactory results are 

 obtained by diminishing the number of the definitive 

 hosts, anophelines. The most vulnerable period in the 

 life-history of these insects is in their larval stage. This 

 is always passed in water. A somewhat detailed know- 

 ledge of the class of breeding-place for the species tha 

 carry malaria in each place is required for effective and 

 economical work in this direction. As these places differ 

 for each species of mosquito, without detailed knowledge 

 money will be wasted and the results cause disappointment. 

 Measures that would be well adapted in places where 

 the malaria is carried by Pyretophorus costalis would be 

 unnecessary, useless ana extravagant, say in Malaya, as 

 they would only result in the destruction of the harmless 

 Myzomyia rossi, and would be insufficient and unsuitable 

 in places where the carrier was M.funesta or M. culici- 

 facies. 



M.funesta, Anopheles niacidipennis, P. costalis and Cellia 

 argyrotarsis or albimanus, are the important carriers of 

 malaria in Southern Europe, Tropical West Africa, and 

 Tropical America, respectively. In Asia, Nyssorhynchus 

 willmori, M. ciilicifacies, N. fuliginosus, and N. stcph- 

 ensij are proved carriers, but many others, such as 

 C. kochi, A. aitkeniy &c., are probably important carriers. 

 Of these there is some similarity in the habits of 

 A. niaculipennis, P. costalis and C. argyrotarsus, and also 

 C. kochi, a suspected carrier. They, all breed in roadside 

 pools, small collections of water, in stagnant water, 

 sometimes very foul, and occasionally in collections of 

 water in artificial receptacles. N. stephensi is usually 

 found in disused or partially used wells, as well as arti- 

 ficial receptacles such as tubs and tanks. 



Their favourite breeding places vary. In Asia the 

 anopheline that is mainly fpund in such situations is 



