FISHES FOR CONTROL OF MOSQUITOES. 23 



The author's observations are in harmony with and explain this 

 statement. It is quite true that in swamp puddles where no other 

 fishes occur culicine mosquitoes of several species will sometimes 

 breed in association with mud minnows. While in the numbers in 

 which they commonly inhabit such places the mud minnows may be 

 considered inadequate in their influence, it is nevertheless probable 

 that without their services a much larfjer number of these mosquitoes 

 would mature. The mud minnows have the very great merit of 

 penetrating the swamp pools, the nooks and crannies of the banks of 

 ponds and ditches, and the dense growths of vegetation, as well as 

 into foul waters, places where no other mosquito-eating fishes native 

 to this region habitually go. Perhaps their chief deficiency is in 

 numbers. Nowhere are they sufficiently numerous to alone keep mos- 

 quito larvae down. However, their cryptic habits cause them to be 

 overlooked, and they are often much more plentiful than one would 

 expect. They lie concealed in mud, under stones and logs, and in 

 vegetation, and large numbers may be had if one goes after them in 

 the right way. They are so hardy that it is probable that they could 

 be propagated artificially and planted in swamps and other waters 

 where they would prove useful. Further work in this direction is 

 recommended. 



COMMON KILLIFISH (Fundulus heteroclitus). 



The common killifish is distributed along the entire Atlantic and 

 Gulf coasts of the United States, according to Jordan and Evermann 

 from Maine to the Rio Grande. This is essentially a tidewater spe- 

 cies, equally at home in the network of thoroughfares and creeks of 

 the salt meadows of New Jersey, the brackish estuaries and affluents 

 of Delaware Bay, and the creeks and ditches of the fresh-water tidal 

 flats of the Delaware River system as far as Trenton. 



In countless millions the killifishes move with the flood tide up the 

 little creeks, draws, and ditches, and as the rising waters spread over 

 the flats, penetrate to all parts of these, retiring again with the ebb 

 to the permanent deeper waters of the larger creeks, rivers, and 

 thoroughfares. Thus twice daily during most of the mosquito-breed- 

 ing season, the entire accessible area of these coastal and river marshes 

 is invaded by hosts of hungry active little fishes seeking for food. 

 In the salt and lower brackish regions this killy is accompanied by 

 several other species chiefly of related cyprinodonts, but in the fresh 

 waters associated fishes are neither numerous nor regular in their 

 movements. As the tide recedes many killies are left stranded, and 

 either remain in little pools or more often wriggle over the mud to 

 regain the receding waters. They have also become landlocked in 

 ponds and obstructed parts of ditches, and will breed in such places 

 as well as normally and usually on the gravelly shallows of the creeks 

 and rivers. Many warm shallow pools literally swarm with the 

 young during the summer. 



The value of this species in limiting the numbers of the salt-marsh 

 mosquitoes is thoroughly established and attested by scores of anti- 

 mosquito workers in New Jersey, New York, and Connecticut. The 

 method of ditching of the salt meadows worked out by Prof, Smith 

 and now extensively applied under the direction of Prof, Headlee 

 and the several county mosquito extermination commissions of New 

 Jersey is essentially based on the principle of concentrating breeding 



