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SOME OBSERVATIONS ON THE BIONOMICS AND BREEDING- 

 PLACES OF ANOPHELES IN SAINT LUCIA, BRITISH 

 WEST INDIES. 



By Lucius Nicholls, B.A., M.B., B.C. (Cantab.), 



Government Bacteriologist, Saint Lucia. 



(Plates VI.-IX.) 



The following article has been written from notes of observations and 

 experiments extending over nearly three years — April 1909 to December 1911. 

 Its main object is an attempt to demonstrate that a true conception of the 

 production of Anopheline mosquitos in a definite country or district can only be 

 formed by a large amount of continual work throughout the seasons of the year. 

 At the present time very numerous observations are still to be made before much 

 generalising should be allowed concerning the breeding-grounds and bionomics 

 of these insects. 



I am here concerned with two closely allied species only, namely, Anopheles 

 (Nyssorhynclms) argyrotarsis and A. (Nyssorhynchus) albimanus. These are 

 well-known malaria-carriers, and I have found oocysts and sporozoits in both of 

 them. Wherever mention is made of Anophelines or larvae in this article, it 

 must be understood to refer only to these two species, for my observations have 

 been restricted entirely to them. 



Natural features of St. Lucia. 



The work has been confined to St. Lucia, a West Indian island, situated 

 13° 50' N. Lat. by 60° 58' W. Long. On the windward side it is washed by the 

 Atlantic Ocean, and on the leeward by the Caribbean Sea. Its greatest length 

 is about 27 miles, and its maximum breadth 14 miles ; it is estimated that it has 

 a superficial area of 238 square miles. 



The island is almost entirely of volcanic origin. It is very mountainous, 

 chains of hills dividing it up into a number of small and large fertile valleys 

 which are covered by alluvial soil. The highest of the hills rises 3,012 feet above 

 sea-level, and they are all densely covered with forests, which occupy the greater 

 portion of the island. Deep rocky ravines either carry the water direct to the 

 coast, or numbers of them coming together form a small river which, increasing 

 in size, courses through the valleys to the sea. 



The two ends of the island are comparatively flat, and this is due to coral 

 formation having been built up on sunken volcanic rocks. There are numerous 

 lagoons of small size in different parts of the island. 



The mean temperature of the island is about 78° Fahr. ; during the cool season 

 it may fall as low as 65°, but it averages about 72° at that time of the year. In 

 the hot months it frequently rises to 90° Fahr. The temperature falls only a few 

 degrees at nights. The appended Table I. (p. 266) shows the rainfall for the last 

 22 years, the average being about 93 inches per year. 



