BREEDING PLACES OF ANOPHELES 257 



coast. Anopheles costalis, the commonest West African anopheline, 

 though it usually breeds in water holes and roadside puddles, especially 

 when fouled by the excreta of man and animals, regularly breeds 

 in domestic pots and barrels in native yards in the town of Lagos 

 (Graham). Anopheles simlensis and Anopheles wiHmori, on the other 

 hand, prefer to breed in clear mountain streams ; Anopheles tiirkhndi 

 is stated by Christophers to breed in river beds in the Punjab, and 

 especially in places where water oozes from sand and where there 

 is much algal growth. 



The peculiarity of each species is of practical importance from the 

 point of view of the prevention of mosquito-borne diseases, and the subject 

 has received a due amount of attention. So far as possible the habitat 

 of the larva has been given in the account of the individual species. 



Although the Anophelina do in this way show a certain amount of 

 choice as regards the places in which they deposit their eggs, they will 

 take advantage of any additional collections of water 



which may come into existence during the rainy season. Permanent and 

 T,, . , ,i -j i r Temporary Breeding 



This is a most important point in the epidemiology of Places 



malaria, for it is the occurrence of these temporary 

 but abundant breeding places which renders possible the great seasonal 

 increase in the numbers present in any locality, and the subsequent 

 outbreak of an epidemic. 



Bentley in his account of malaria in Bombay, where Anopheles 

 stephensi is the incriminated mosquito, draws a useful distinction 

 between the permanent and temporary breeding places. In Bombay its 

 permanent breeding places are the numerous wells, most of which 

 are either actually within the houses or in close proximity to them, 

 and also water cisterns, garden tanks, and similar places ; -in these 

 situations larvae are to be- found in small numbers throughout the 

 year. During and after the rains, however, stephensi breeds in surface 

 pools, tubs, buckets, old earthenware vessels, etc., near the houses, 

 and it is to the mosquitoes hatched out in such places that the sudden 

 'ncrease in the prevalence of malaria is to be traced. The explana- 

 tion of the fact that the larvae are never found in large numbers in 

 the permanent breeding places is that the conditions which have 

 allowed the species to become established in these situations have also 

 permitted of the establishment of their natural enemies, such as preda- 

 ceous larvae, small fish, etc., while in the temporary breeding places 

 the larvae can grow, and the imagines hatch out, before the natural 

 enemies gain a footing ; not only do a larger proportion of the "eggs 

 33 



