Procke:dings q-^ Fii^TH Annual, Meeting 109 



On the other hand, LePrince and Orenstein^ found the Ano- 

 pheles flying either against the v/ind or at right angles to it. 

 Russell, however, records Anopheles annulipalpis as coming 

 aboard ship on a breeze from land. 



The zone of the house mosquitoes described by Headlee did 

 not extend in the direction of the favorable winds. The mosqui- 

 toes seem to have moved in the direction of dense population. 



The migrations of the fresh-water swamp mosquito extended 

 southward and eastward much further than northward or west- 

 ward, while the more favorable winds would seem to urge them 

 in opposite directions. It is quite possible that the ranges of 

 low mountains with which the home of this brood of the swamp 

 mosquito was surrounded may have had something to do with 

 the direction of migrations, for the openings lay to the south 

 and east. To go to the north and w^est was to encounter a suc- 

 cession of ridges, while to migrate southward meant much easier 

 going. 



CONCWSIONS 



The ordinary short flights of all species between food and 

 breeding places that serves to keep the species going in localities 

 where they are already established are in all probability initiated 

 by food and breeding-place odors. That these stimuli may ex- 

 cite movements of considerable distances is indicated by the 

 studies of LePrince and Orenstein in Panama.'^ 



When, however, we consider the long-distance flights of any 

 species, the breeding conditions of which have been carefully 

 studied, we find that they arise only where the species concerned 

 has bred very intensely over a large area. 



Naturally, under these conditions the food supply would be 

 less than normal and the flight might be due to that fact. 



Air currents, so long as they are not too high to prohibit move- 

 ment, would seem not to affect in any important way the short 

 ordinary flights, but seem to be a determining factor in long- 



" Ivoc. cit. 

 ^ Loc. cit. 



