784 



SCIENCE 



[N. S. Vol. XLIII. No. 1118 



MOSQUITOES AND MAN 



A UNIQUE deduction, and one likely to be of 

 great value to sanitarians has been reacted as 

 one of the results of the work done in the 

 Canal Zone by Major P. M. Ashburn, Medical 

 Corps, U. S. Army. As general inspector, 

 health department. Canal Zone, Major Ashburn 

 became intimately acquainted with the breed- 

 ing conditions there, and one result of his ob- 

 servation may be summed up in his statement 

 " the malarial mosquito follows man." This 

 means also that their breeding places are nor- 

 mally within convenient reach of human habi- 

 tation and becomes a very effective as well as 

 an entirely new viewpoint of already recog- 

 nized conditions, and a viewpoint it would be 

 wise to keep in mind wherever health, effi- 

 ciency and mosquito control are to be con- 

 sidered. 



Major Ashburn in referring to the well- 

 proven flight of anophelines of " more than a 

 mile from their place of breeding " draws at- 

 tention to the facts^ that there is at this partic- 

 ular location " a large area where the condi- 

 tions for breeding are unusually favorable . . . 

 an enormous amount of breeding . . . lack of 

 abundant human blood for food in the neigh- 

 borhood of the breeding place, the presence of 

 ahundance of food (a town) at a distance of a 

 mile," and goes on to say " were there another 

 town within two hundred yards or a quarter 

 or half of a mile, the chances are that the town 

 a mile away would scarcely notice any change 

 in the number of mosquitoes." " In fact such 

 has been the experience at several places on the 

 Isthmus," and, referring to another location 

 adds : " The conditions favored a big flight, 

 but a human barrier in the neighborhood 

 served to check it and make the increase of 

 mosquitoes merely a local one." 



In another paper^ Major Ashburn speaks of 



1 Ashburn, P. M., Major, Medical Corps, IT. S. 

 A., "Elements of Military Hygiene," 2d ed. 

 (1915), pp. 285. 



2 Ashburn, P. M., Major, Medical Corps, IT. S. 

 A., general inspector, health department, Panama 

 Canal, "Some Observations Bearing on the Con- 

 trol of Malaria." Eead before the Canal Zone 

 Medical Association, late in 1914. 



the conditions in the Canal Zone where places 

 that had been " great hot beds of malaria, and 

 great breeding places for Anopheles alhimanus, 

 now, since their depopulation, have very few or 

 no Anopheles " mentioning the water works at 

 Miraflores, Cocoli, Ancon Village as examples 

 and refers to a few instances where Anopheles 

 which " were supposed to have come from con- 

 siderable distances, the situations were found 

 controllable by intensive effort expended close 

 at hand," while the hydraulic fills at several 

 places which gave rise to much increased 

 breeding did not give rise to flights of great 

 length, because " there was food nearer at 

 hand." 



ISTatuxally the interposition of " an animal 

 barrier between extensive Anopheles breeding 

 places and human habitation " was considered, 

 but this was found to have already been proven 

 of small or no value. 



Major Ashburn then evolved an hypothesis 

 including " (.4) Parasitism, (B) Long Flights, 

 (C) Anopheles hreeding far from man not 

 malarial carriers." It is with the last point 

 we are most concerned, although, of course, 

 the three parts are really interdependent. 



Major Ashburn calls attention to the fact 

 that Anopheles apicimaculatus, not a malaria 

 carrier, was often found breeding 800 yards 

 from himian habitation, and that even a tem- 

 porary construction camp of a large gang of 

 negroes was enough to bring malaria carriers 

 to a given place, and the removal of the 

 laborers was followed by a discontinuance of 

 the breeding of malaria carriers at that place. 



Finally, at a contractor's camp, established 

 N"ovember 26, 1913, at Cano Saddle, in a previ- 

 ously uninhabited location, hand catching of 

 mosquitoes showed an increase in the weekly 

 takings of malaria carriers as indicated in the 

 following partial table: 



Week Ending Malaria Carriers 



December 6, 1913 6 



December 13, 1913 34 



December 20, 1913 165 



December 27, 1913 115 



January 31, 1914 1,211 



March 7, 1914 3,277 



May 9, 1914 87 



