64 PREVENTIVE AND REMEDIAL WORK AGAINST MOSQUITOES. 



telling the rest of the family. In a day or two a member of the family 

 remarked that there were no wrigglers in the water. Mr. Anderson 

 verified the observation, and after many months was able to state 

 that no mosquito larvae had been seen since. 



The common goldfish proves to be an excellent mosquito feeder 

 and during the summer of 1901 Mr. Jacob Kotinsky, then of the 

 Bureau of Entomology, conducted a series of laboratory experiments 

 with goldfish in an aquarium. He found that they were voracious 

 feeders on mosquito eggs, preferring them to larvae. He further 

 noticed that the fish, after taking several larvae into the mouth, would 

 eject some of them. Further, he found that in a large jar containing 

 four goldfish and many hundreds of mosquito larvae, a few of the 

 larvae succeeded in transforming and emerging as adult mosquitoes. 

 The food supply was evidently in excess of the capacity of the fish. 



At an earlier date than this Mr. H. W. Henshaw, of the Biological 

 Survey of the United States Department of Agriculture, was staying 

 at Fruitville, near Oakland, Cal. The house and neighboring houses 

 were badly infested with mosquitoes. He found the source of supply 

 to be a lily pond about 7 by 12 feet in size and fully 3 feet deep, which 

 was fairly swarming with larvae. He got a half dozen goldfish from 

 San Francisco and put them into the pond. The following day they 

 were so badly bloated that they could hardly swim, and in a few 

 days there was not a single larva left. The fish bred in the pond and 

 from the time of their introduction there was a very marked decrease 

 in the number of mosquitoes in that general locality. 



Mr. William Lyman Underwood, of the Massachusetts Institute of 

 Technology, in Science for December 27, 1901, described an interest- 

 ing experience with goldfish: 



About six years ago, at my home in Belmont, near Boston, Mass., I constructed a 

 small artificial pond in which to grow water lilies and other aquatic plants and also 

 to breed, if possible, some varieties of goldfish — though the latter object was a second- 

 ary consideration. The advisability of making this pond had been somewhat ques- 

 tioned on account of its close proximity to my house and the fact that such ponds are 

 likely to become excellent places for the propagation of mosquitoes. Nevertheless, 

 the plan was carried out and the pond was stocked with goldfish taken from natural 

 ponds in the vicinity where they had been living and breeding, to my personal knowl- 

 edge, for a number of years. 



The aquatic garden has proved a success and the goldfish have meantime thriven 

 and multiplied. Moreover, no mosquitoes attributable to the pond have appeared 

 and I have been unable to find any larvae in it, although I have searched repeatedly 

 and diligently for them. I have always believed that the absence of mosquito larvae 

 from this pond was due to the presence of the goldfish, and I have so stated in a paper, 

 "On the Drainage, Reclamation, and Sanitary Improvement of Certain Marsh Lands 

 in the Vicinity of Boston " in the Technology Quarterly, XIV, 69 (March, 1901), as 

 follows: "In the water (of this pond) are hundreds of goldfish that feed upon the 

 larvae of mosquitoes and serve to keep this insect pest in check." * * * I took 

 from the pond a small goldfish about three inches long and placed it in an aquarium 

 where it could, if it would, feed upon mosquito larvae and still be under careful obser- 

 vation. The result was as I had anticipated. On the first day, owing perhaps to the 





