DESTROYING AND REPELLING MOSQUITOES 87 



ever be able to give relief from Anopheles mosquitoes. 

 Moreover, the fishes must be top-feeders in order to find 

 the larvae lying on top of the water. 



The goldfish is a good species for introduction into 

 pools, especially ornamental plant pools. This fish is 

 used in Japan for this purpose. In fact, goldfishes, when 

 grown commercially in that country, are fed largely on the 

 larvae of mosquitoes. W. L. Underwood describes the 

 work of goldfish in devouring mosquito larvae as follows : 

 " 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 larvse and 

 still be under care- 

 ful observation. 

 The result was as 

 I had anticipated. 

 On the first day, 



Owing perhaps to Fig. 30. — Roach or golden shiner. 



the change of en- 

 vironment, and to being rather easily disturbed in its new 

 quarters, this goldfish ate eleven larvae only in three hours ; 

 but the next day twenty were devoured 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." Un- 

 fortunately goldfish grow rather large and tend to become 

 cannibalistic. 



The roach, or golden shiner (Fig. 30), is also an admirable 

 fish for pools and ponds. It is widely distributed and 

 is very abundant. Moreover, it is a very active fish, 



