256 THE MOSQUITOES OF NEW JERSEY 



for the reason that pike and other predaceous fishes collect about the 

 deep holes and spring places in winter, and Gambusia would have little 

 chance for escape, whereas in the spring they could find protection 

 among the plants and in the shallows where the others could not reach 

 them. Another consideration is that in fall we should be submitting a 

 few thousands to new and unfavorable conditions at the most unlikely 

 time of the year, whereas if we put the same number out in the spring, 

 by fall we can reasonably expect that there will be tens of thousands, 

 thoroughly familiar with and adapted to the waters in which they began 

 life, and, having known no other, there will be no question except that of 

 temperature involved. 



"I have seen Gambusia collected in vast numbers where there was thin 

 ice, at Cape Charles, Virginia, and I have no doubt they passed the 

 winter in those places, where probably the ice was at times two or three 

 inches thick, or even more. 



"This would be an ideal species to introduce into ornamental ponds 

 in which aquatic vegetation forms an important feature. Such ponds 

 having no fish save those which are placed in it would allow this little 

 species to develop unchecked and would absolutely prevent all danger 

 of mosquito breeding." 



Since Dr. Smith's report, the top minnow has been located in certain 

 sections of southeastern New Jersey, and various attempts have been 

 made to plant it, but in no case has it been able to persist much out of 

 its natural range. It goes along during the summer, but disappears dur- 

 ing the winter. Although the experience has been discouraging it has 

 not been really conclusive. Furthermore, carefully directed experiments 

 should be made. 



But throughout the recorded history of the mosquito, after the ut- 

 most has been done by natural enemies, the pest still appears at times 

 and places in terrible proportion. 



The activity of animal and plant enemies of mosquitoes seems to be 

 at its maximum in permanent bodies of water with a reasonably fixed 

 level because such water condition affords many of these animals a 

 sufficient continuous food supply to preserve their lives and activity. 



In midsummer a brood of mosquitoes can hatch from the eggs, com- 

 plete larval development, complete pupation, and emerge as adults in 

 a period of from seven to ten days. This life cycle is extremely short, 

 materially shorter than the life cycles of the better known natural 

 enemies. Since mosquito larvae and pupae appear suddenly in immense 

 numbers, stay only a short time, and fly away as adults, the mosquito 

 cannot serve as a continuous article of diet. 



