DIPTERA OF iMINNKSOTA. 47 



Remedies and Means of Preiention. 



First, the filling in or draining of swampy marsh land in the 

 vicinity of dwellings; the evening of shore lines of ponds and lakes, 

 where possible, making the same regular, and thus doing away with the 

 small, shallow inlets and wet depressions, which afford breeding places. 

 Ponds, the surfaces of which are well covered with leaves of a(|uatic 

 plants, are not so nnich infested as o])en shallow water, because the 

 female mosquito is discouraged in trying to reach the surface of the 

 water for egg laving. On the other hand, in ponds where there are 

 large leafed plants growing beneath the surface, the wigglers above 

 the leaves are more or less protected from the view of the fish below, 

 which would otherwise prey upon them. 



Kerosene is a good agent used against these pests upon ponds, 

 drains and tanks where the use of it does not interfere with the le- 

 gitimate use of the water. Even in tanks where the water is used for 

 the needs of stock or man, if an arrangement is made to draw the 

 water from below, a film of oil can be made to cover the surface 

 without affecting the qualit\- of the water. The use of oil is based 

 upon the fact that the larval and pupal mos([uito have to come to the 

 sin-face for air, the air entering through certain tubes adapted to that 

 end. The slightest contact with oil is- fatal to them. One applica- 

 tion every three weeks should be sufficient. It is preferably sprayed 

 over the surface, though if it be simply poured on the surface, it will 

 gradually cover the entire surface area. As long as a film is seen 

 on the surface no treatment is necessary. 



A cjuite important remedy is the introduction of fish, the stickle- 

 backs, minnows, or common sun fish, into ponds and elsewhere, 

 wherever kerosene cannot be used. These prey upon the wigglers, 

 consuming large numbers. 



The covering of cisterns and rain barrels, preventing adults from 

 reaching the water and laying their eggs thereon, is a thought which 

 would occur to any one knowing their habits. 



Most compounds devised as preventives for application to the 

 face and hands are either nauseating or ineft"ective or both. The 

 writer in common with many others, has found, however, that oil 

 of citronella, for sale at most drug stores, is the best preventive, and 

 its odor not at all disagreeable. This should not be diluted, and should 

 be applied to the face, neck and hands where one is exposed to the 



