LIFE HISTORY AND SEASONAL PREVALENCE 121 



In July and August last, my duties involved an extensive 

 tour through the province daring the rainy season. In the 

 early part of the period it was evident that though Ano- 

 pheles larvte were common, they had not long been so, as 

 even in places where they were plentiful, I could find 

 no adults. It was not indeed till the end of the month that 

 I began to find them at all commonly in bungalows. The 

 situations, however, in which I found the larvne entirely 

 upset all the notions I had gathered from recent writings on 

 the subject. I began, of course, by looking for the typical 

 Anopheles pool of Ross, but such as I found never held any 

 of the expected larvae, and the first place I met with them 

 was in the garden of the Meerut Club, in the small irriga- 

 tion tanks described in the next chapter Here they were 

 present in enormous numbers, sometimes alone, but more 

 frequently in company, and apparently on excellent terms 

 with the larvEe of C. fatigans. It was, however, noticeable 

 that while the Culex larvae for the most part remained in the 

 middle of the tanks, those of Anopheles generally kept them- 

 selves floating with their tails touching its side walls, and 

 so might easily be overlooked. In my subsequent wander- 

 ings, I met with Anopheles larvas in a variety of situations, 

 but always these small irrigation tanks were the " surest 

 find," and further I never met with them at any distance 

 from human habitations, so that I am inclined to suspect 

 that females are unable to mature and deposit their eggs 

 until they have had a feed of blood. I have also met with 

 Anopheles larvae in muddy pools of some size in brick-fields, 

 in the overflow from stand-posts in large cities supplied with 

 a regular filtered water supply, and even in a very shallow 

 depression in the concrete surface of the platform of a bust- 

 ling railway junction, also fed by a stand-post. 



In Hong Kong, Dr. J. C. Thomson writes, in The 

 Government Gazette of November 24th, 1900. "The usual 

 habitat of the larvae of the Anopheles Mosquito is the natural 

 water courses, and their favourite locations little breaks in 

 the rocky surface by the side of the stream, where the 

 merest trickle from the stream itself prevents entire stag- 

 nation, and where the)-e is no through-wash." This, it will 



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