NATURAL ENEMIES 61 



ponds, reservoirs, springs, cisterns, tanks, and the like 

 are among the instances in which surface-feeding 

 minnows may be found useful. 



The common goldfish [Carassius auratus) is at the 

 same time one of the most ornamental as well as effi- 

 cient fishes in this respect. The following quotation 

 is apropos taken from Howard, after Underwood, re- 

 ferring to an ornamental aquatic garden near Boston, 

 in which the mosquitoes were kept in check by gold- 

 fish : "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 observation. ... In the first 

 day, owing perhaps to being rather easily disturbed in 

 its new quarters, this goldfish ate eleven larvae only in 

 three hours, but the next day twenty-three were de- 

 voured in one hour; and as the fish became more 

 at home the 'wrigglers' disappeared in short order 

 whenever they were dropped into the water. On one 

 occasion twenty were eaten in one minute, and forty- 

 eight within five minutes. This experiment was fre- 

 quently repeated and to see if this partiality for insect 

 food was characteristic of those goldfish only which 

 were indigenous to this locality experimented with, 

 some said to have been reared in carp ponds near 

 Baltimore, Maryland, were secured. The result was 

 the same. . . ." Similar results have been attained 

 in a number of places both on the Atlantic and Pacific 

 coasts. 



