92 AGRICULTURAL EXPERIMENT STATION. 



Fish versus Mosqidto LarvcE. 



Of all the natural enemies of mosquito larvae, fish are the most 

 important from the practical standpoint because they can be trans- 

 ported to places where they are needed, because they will stay 

 where put and because they live throughout the' season. 



In order to determine just which of our New Jersey species 

 are effective I intrusted the general subject to Mr. William P. 

 Seal, of Delair, New Jersey, because of his experience in collect- 

 ing, observing and studying these fish. Practical experiments 

 were made by Mr. Seal in his tubs and ponds at Delair, and col- 

 lecting trips to determine the presence of certain species were 

 made to the Delaware, to Townsends Inlet and to Cape May. 

 The reports on experiments and on the collections made are con- 

 tained partly in letters, partly in a more formal list of important 

 species. 



But beside these, more systematic studies, experiments and 

 observations were also made by Mr. Brehme, at Newark, and 

 by Mr. Viereck, at Cape May. All these observations will be 

 -collated and each observer credited; but in general where no 

 specific credit is given, Mr. Seal is quoted. Most of the strictly 

 descriptive matter is from Dr. Tarleton H. Bean's "Fishes of 

 New York." 



"The number of species of fish to be found in the waters of 

 New Jersey where mosquitoes might be expected to breed, and 

 which might be looked upon as destroyers of them, is compara- 

 tively small ; but during the late spring, summer and fall, these 

 few species abound in the young stages in almost incredible num- 

 bers. While the very young fry are incapable of devouring the 

 full grown mosquito larvae, they can devour them as they emerge 

 from the tgg, at which time they are very minute ; so that it may 

 be said that by the time a fish is a week or two old, it is prepared 

 to take up the work of destruction. And it can be said with 

 confidence, as a result of continued observation, that in the water 

 to wdiich these small species have free access, mosquitoes cannot 

 propagate. An exception must be made of the genus Anopheles 

 in places where there are dense masses of aquatic plants. 



"It is rather a remarkable fact that of the large number of 

 species of fish to be found in the waters of New Jersey, there 

 should only be some nine or ten that can be considered as at all 

 useful as mosquito destroyers ; but when the wide distribution 

 and abundance of these few species and the character of the 

 water in which mosquitoes breed are taken into consideration it 

 does not seem so strange. Fortunately the young of these few 

 useful species abound in enormous numbers during the warm 

 months in every accessible place where mosquitoes might breed. 



