118 SCIENTIFIC REPORTS OF THE AGRICULTURAL RESEARCH 



eggs and aquatic or semi-aquatic larvse showing somewhat 

 unusual characteristics. In view of the possibility that 

 these flies may convey disease, observations on this curious 

 and little-known group will be continued. 



III. Experimental and Practical Work on Mosquitos. 



Practical anti-mosquito work has consisted in the 

 continuance of the mosquito campaign in Pusa. So far, 

 with the aid of a very limited temporary staff, this work 

 has, I think, sufficiently justified itself to warrant an exten- 

 sion on the " trap-breeding " lines first advocated by me in 

 connection with the Stegomyia investigation of a few years 

 ago. The main idea of trap-breeding is to supplement the 

 ordinary (and almost inevitably incomplete) destruction of 

 natural breeding-places by supplying a large number of 

 alternative breeding-places of a suitable type which will 

 absorb the local egg-supply, but which are in one way or 

 another kept under control so that none of the eggs laid in 

 them shall reach maturity. 



The method has now been tried in various parts of the 

 world and seems to have proved uniformly successful. It 

 enables one materially to economize energy in reducing the 

 mosquito population, and minimizes the difficulties asso- 

 ciated with imperfect inspection and the discovery by the 

 mosquitos of unnoticed or inaccessible breeding-places, this 

 latter being the main and frequently unavoidable difficulty 

 of the purely destructive methods generally advocated. 



Proposals are being submitted for the construction of a 

 number of permanent breeding-places in order to extend the 

 work on the above lines, most of the breeding-places would 

 take the form of small ornamental fishponds inspected and 

 stocked with suitable local fish by the campaign staff. 



A certain number of organic compounds have been 

 tested as larvicides, but no results of any practical interest 

 have been obtained except in the case of the Xanthates, 

 which have a very high toxicity for mosquito larvae. 



A long series of experiments has been carried out with 

 the object of ascertaining the factors which influence mos- 



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