04 MOSQUITOES 



tlie shore lino, crossed Trii|)aIacios Hay, tliree miles, Caraiicaliua 

 Bay, at Pass, :500 yards, Keller's Bay, at Pass, halt' mile, Cox's 

 Bay, one and a half miles, and ]^)rt Lavaea Bay, tour miles. 



It may incidentally be stated that malarial mosquitoes 

 of the genus Anopheles seem much loss capable of ox- 

 tended flight than the commoner mosquitoes of the genus 

 Culox. Dr. V. A. Young, of the British Ainiy Medical 

 Service, on his way home from Shangliai, Avhore he had 

 been conducting experimental work against malarial mos- 

 quitoes, called on me in February, 1901, and stated that 

 it was his firm conclusion that, as a rule, Anopheles will 

 not fly over two hundred yards, and that a breeding-place 

 more than two hundred yards from the house will not 

 suj)ply malarial mosquitoes to that house, provided there 

 are other houses nearer. He mentioned a number of cir- 

 cumstantial instances supporting this view. Christo- 

 phers and Stephens, however, in their reports on the 

 malarial expedition to Sierra Leone, state that it is cer- 

 tain that under some circumstances Anopheles may fly 

 much greater distances than has been sujiposed. In one 

 small inland hous(^ which had been occnpiod by one old 

 man, five or six Anopheles were to be caught each morn- 

 ing. These were fr(^shly hatched and could only be de- 

 rived from a brooding-place throe to four hundred y:irds 

 away. In another place the same writers show a flight 

 of six hundred yards. But, aftcn- all, what are even six 

 hundred yards ? In an effort to free a locality from ma- 

 hiria such distances become insignificant. 



On the whole, it seems to the writoi- tliat in almost no 



