258 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



complained. They had paid their good money but there were just 

 as many mosquitoes as before. 



Much searching was therefore done for rain water barrels, though a 

 thousand of thenj could not have produced all the mosquitoes present. 

 They fairly swarmed in protected corners of buildings, under verandas, 

 and in shrubbery. They were small and entered houses through the 

 meshes of the screens. They were innocuous during the day, but as 

 soon as it was dark they began to sing and to bite. Unless the windows 

 were kept closed or mosquito bars placed over the bed, a good night's 

 sleep was impossible. 



On August 5, one of my assistants, Mr. L. B. Ripley, was sent to 

 examine all pools in Edgewood Park. He happened to dip into the 

 edges of the main stream (West River) and obtained wrigglers, espe- 

 cially in the little coves and in other places where, choked by vegetation 

 or rubbish, the water was quiet. In the middle of the stream there was 

 no breeding; the current prevented it. Small pools under the Whalley 

 Avenue bridge were literally alive with-CuJex larvae. 



Mr. Ripley reported the facts to me, and then the stream was ex- 

 amined toward the north and west. In the west branch, nearly as far 

 as the Pond Lily Company's Dye Works, wrigglers were extremely 

 abundant, especially along the edges and outside of the main current 

 which was slight on account of the very low water, almost no rain hav- 

 ing fallen in June and July. At one dip of the ladle, which holds about 

 a gill, 200 wrigglers were taken. 



It was apparent that the fish had been killed or driven from the 

 water by the dye stuffs from the Pond Lily Company's factory, though 

 rain-barrel mosquitoes, which often breed in strongly polluted water, 

 were able to breed in this stream. Heavy rains would probably have 

 flushed out the stream but with the lack of rain, and the absence of fish, 

 mosquitoes took possession of the water and were breeding there 

 literally by millions. These wrigglers clustered around stones, leaves, 

 or other objects in the water and could be seen from the banks at a 

 distance of perhaps 15 feet; little or no breeding was found in the other 

 branches of West River where the water was clear. 



Thus the mystery had been solved and tlie source of the mosquito 

 nuisance had been discovered. Up to this time the main stream had 

 not even been suspected as a possible breeding place. 



During the next few days the surface of the river, where mosquito 

 wrigglers could be found, was sprayed with oil from a point opposite 

 Ramsdell Street near the Pond Lily Dye Works to the Whalley Avenue 

 bridge, a distance of nearly one and one-half miles of the winding 

 course of the stream. Also the canal near the paper mills, and many 

 detached breeding pools that in high water are connected with the 



