i68 N. J. Agricultural Experiment Station, Bulletin 348 



The observations of practically all investigators indicate that the 

 salt-marsh species in long migrations travel with the wind. 



On the other hand, LePrince and Orenstein found the Anopheles 

 flying either against the wind or at right angles to it. Russell, how- 

 ever, 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 mosquitoes 

 seem to have moved in the direction of dense population. 



The migrations of the fresh- water swamp mosquito extended 

 southward and eastward much farther than northward or westward, 

 while the more favorable winds would seem to urge it 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 sur- 

 rounded may have had something to do with the direction of migra- 

 tions, for the openings lay to the south and east. To go to the north 

 and west was to encounter a succession of ridges, while to migrate 

 southward meant much easier going. 



Conclusions 



The ordinary short flights of all species between food and breed- 

 ing places that serve to keep the species going in localities where they 

 are already established, in all probability are initiated by food and 

 breeding-place odors. That these stimuli may excite movements of 

 considerable distances is indicated by the studies of LePrince and 

 Orenstein in Panama. 



However, when, we consider the long-distance flights of any spe- 

 cies, 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. 



Natm-ally, 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 movement, 

 would seem not to affect in any important way the short ordinary 

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

 ments. Ordinarily the flight in such cases goes with the slow- 

 moving, warm, damp wind, but modifications in direction of flight 

 may be due to mountain ridges and possibly other factors not at pres- 

 ent recognized. 



