32 3I.0S(jl'IT(>I<:S 



ill the closed sewers in AVasljin<,'-ton, deserves more de- 

 tailed mention than we have given it. His house in 

 northeast Washington being infested with mosquitoes 

 autl uo exposed standing water occurring in the vicinity, 

 he thought of covering the small perforated sewer-trap 

 in his back yard with a wire screen. To prevent the pos- 

 sibility of moscpiitoes entering the screen from the out- 

 side, a layer of cotton was placed around the edge of the 

 trap on which the screen rested. On August 2J:tli two 

 females of Cnlcx j^ungais were found under the screen. 

 September 3d another was found in the same place, but 

 it went back to the sewer as soon as the rajs of the sun 

 struck the screen. September Gth, lOtli, and lltli, five 

 more were caught. Female moscpiitoes in search of 

 breeding-places had evidently tlowu through the sewer- 

 trap perforations, had found standing water in the sewer 

 and laid their eggs, from which a generation of adults 

 was developed. 



There are other localities in AVashingtou, far removed 

 from the Potomac River front, where mosquitoes are more 

 or less abundant, and where there seems to be no standing 

 water in which they can breed. It therefore seems rea- 

 sonably sure that this sewer-breeding may be rather com- 

 mon in certain cities where the general slope is so slight 

 that the water may almost stand still for a few days, in 

 the absence of very heavy rains which tlusli the sewers. Of 

 course such breeding will easily be stopped by a little 

 neighborhood work, either by occasionally i)ouring a little 

 kerosene down the sewer-traps or bj' covering them Avith 

 a wire screen, as did Mr. Pergande in his experiments. 



