^4 MOSQUITOES 



the shore Hue, crossed Trupahieios Bay, three miles, Carancahua 

 Bay, at Pass, 300 yards, Keller's Bay, at Pass, half mile, Cox's 

 Bay, one and a half miles, and Port Lavaca Bay, four miles. 



It may incidentally be stated tliat malarial mosquitoes 

 of the genus Anopheles seem much less capable of ex- 

 tended flight than the commoner mosquitoes of the genus 

 Culex. Dr. F. A. Young, of the British Army Medical 

 Service, on his way home from Shanghai, where 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 

 supply 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 supposed. In one 

 small inland house which had been occupied by one old 

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

 ing. These were freshly hatched and could only be de- 

 rived from a breeding-place three to four hundred yards 

 away. In another place the same writers show a fliglit 

 of six hundred yards. But, after all, what are even six 

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

 laria such distances become insignificant. 



On the whole, it seems to the writer that in almost no 



