Hibernation. 



prevalence of A. culicifacies and A. rossi in the Punjab. It will be 

 seen that A. culicifacies begins to be prevalent in May, while A. rossi 

 does not appear until July, and that both species diminish rapidly in 

 numbers towards the end of November. A. fuligmosus is most 

 prevalent in the Punjab in September, but as the winter advances 

 it does not decrease in numbers nearly to the same extent as other 

 species do, and throughout the winter its adults may be found with- 

 out difficulty in houses, and its eggs and larvae in newly-formed 

 breeding places. A. pulcherrimus is also, to some extent, a " winter 

 species " in the Punjab, and non-hibernating specimens can be col- 

 lected in moderate numbers even during the coldest months. Re- 

 garding the seasonal prevalence of other species which occur in the 

 Punjab, and of all species which occur in other parts of India, 

 little or nothing is known. 



THE METHODS BY WHICH ANOPHELES TIDE OVER THE WINTER. 



Two methods of which mosquitoes tide over the cold season are 

 usually described, viz. (1) by the hibernation of adults, and ( 2) by the 

 hibernation of larvae. Very few observations on this important 

 subject have, however, been made in any part of the world, and it 

 is by no means certain that these are the sole methods by which 

 the disappearance of " anopheles" during the winter, and their 

 reappearance in the spring, may be accounted for. The only 

 observations recorded in India appear to be those made by one of 

 us in connection with the anti-malarial operations carried out at 

 Mian Mir in the Punjab during 1901-1^03. These were as follow : 



(1) During the winter not a single adult A. rossi or A. culicifacies 

 could be found by the most careful search, or by burning culicidal 

 substances, in any house, stable, shed, or other place where it seemed 

 probable mosquitoes might hibernate during the cold weather ; 



(2) no eggs or larvae of either of these species appeared in newly- 

 made breeding places ; (3) in permanent breeding places, which 

 had remained since the summer, many hibernating larvae of 

 .4. culicifacies were found, but no larvae of a. rossi were present ; 

 (4) many adult A. fuligmosus and a few adult A. pulcherrimus 

 were found throughout the winter in houses and sheds. The 

 habits of these species were, however, the same during the winter 

 as during the summer, and they did not " hibernate " in the correct 

 sense of the term ; ( 5 ) eggs, young larvae and pupae of these two 



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