Breeding grounds of " Anopheles" 



grounds. It would appear probable, from the observations just re- 

 corded, that such suppositions are incorrect, and if this is so, the 

 task of materially reducing the numbers of " anopheles " in any place 

 will undoubtedly be one of great magnitude. 



THE BREEDING PLACES OF ANOPHELES. 



The fact that, taking " anopheles " as a whole, it is almost impos- 

 sible to mention any collection of water in which their larvae may 

 not occasionally be found, is now well known. It has an important 

 application when any practical measures at extermination of larvae 

 are attempted, in that it leads us not to overlook even the most 

 unlikely places in our search for larvae ; for unless we search systema- 

 tically every collection of water, temporary or permanent, we may 

 easily allow an important breeding place to remain, when we think 

 all possible breeding grounds have been done away with. 



But under favourable conditions by which we mean abundance 

 of breeding places of all kinds near at hand " anopheles " will not, 

 as a rule, lay their eggs in an unsuitable collection of water, and 

 there is no doubt that, under such circumstances, not only do these 

 mosquitoes select their breeding places, but that each species has a 

 particular kind of breeding ground that it prefers over any other. 

 This observation which was first made by Dr. Christophers at Jal- 

 pniguri in Bengal, is a very important one. 



At Jalpaiguri two species of anopheles were common, viz. ^. 

 rossi Giles, and .4. nigerrimus. The breeding places of A. rossi 

 were invariably found to be the small, shallow, muddy puddles and 

 pools close to, and among, the native huts. A. nigerrimus, on the con- 

 trary, was breeding entirely at some ditance from the village in the 

 deep natural pools of a swampy marsh. A. rossi larvae were never 

 found in these pools, and A. nigerrimus larvae never in the shallow 

 muddy pools near the huts. 



In the Duars, the same selection of breeding places by A . rossi 

 and A. listoni, was found to exist, A. rossi larvae being found only 

 in the shallow muddy pools near the coolie huts, and A. listoni 

 larva? ( the adults of which were nevertheless more common in the 

 huts than those of A. rossi) being only found at some distance 

 from the lines in the small clear pools formed by a mountain stream, 

 and by dipping in the water among the grass and weed at the edge 

 of the stream itself. 



