REPORT OX AIOSQUITOES. 95 



the insects disappeared. This was done under so many condi- 

 tions that no doubt exists of the fact that the mosquito larvae 

 are a normal food of the Httle fish. 



More specific experiments were made by Mr. Viereck at Cape 

 May. Two pools were selected early in June, each about three 

 square yards and each containing by estimate about 20,000 wrig- 

 glers. Into one of these sixteen Fmiduhis were put, into the 

 other fifteen Cyprinodon. The Fundidus did not find the water 

 to their liking and devoted their energies to trying to get away. 

 The water was very foul and stagnant and it was afterward 

 found that these fish would not live under such conditions. 

 Cyprinodon was less particular and in four days had devoured 

 the majority of the larvae — say 12,000 in four days, or 200 per 

 day to each fish. 



July 1 6th another experiment was made, and seventeen specie 

 mens of Fundvdus ranging from two and one-half to three and 

 one-half inches were put into a pool from two to three inches 

 deep with a surface area of two square yards and containing 

 nearly one thousand wrigglers. In half an hour more than 90 

 per cent, of the larvae had disappeared and the fish were yet at 

 work. 



Then a trial was made of the comparative hardiness of 

 Cyprinodon and Funduius by placing both in tubs with an inade- 

 quate supply of water, and in this test Funduius did better, 

 Cyprinodon becoming asphyxiated first. 



A further test was made July i8th, when four large pans were 

 stocked, each with a large dipper full of well-grown larvae. No. 

 I was kept as a check; in No. 2, four small Cyprinodon were 

 placed; in No. 3, six medium-sized Cyprinodon were put, and 

 No. 4 received two medium-sized Funduius. It was intended 

 that each pan should contain about the same number of wrig- 

 glers, but they were not counted. Three days later few larvae 

 remained, the change to the pupal stage going on so rapidly that 

 to prevent the issuance of adults the experiment was closed. 

 Pan No. I now contained 832 larvae and pupae, and this was 

 assumed as the number originally placed in each. Pan No. 2 

 contained 248 larvae and pupae, hence four small Cyprinodon had 

 eaten 584 wrigglers. Pan No. 3 had no larvae and pupae, hence 

 six medium-sized Cyprinodon had eaten 832 larvae. Pan No. 4 

 had 133 larvae and pupae, hence two medium-sized Funduius had 

 eaten 699 wrigglers ; surely an excellent record for the little 

 fellows ! 



In the experimental ponds, brood 6 at Cape ]\Iay developed 

 toward the end of August and then they began to drv up. The 

 fish which had bred in the ponds retreated to the deepest pools 



