INFLUENCE OF ENVIRONMENT 24,1 



"The studies on food for larvae were continued in 1925. A number of 

 sampling places were selected and water taken from these places at 

 regular intervals of fourteen days. The work was started in the middle 

 of March and terminated in several cases at the end of the first week of 

 October. The samples were analyzed chemically and microscopic deter- 

 minations made of the life they contained. The data in hand is quite 

 voluminous and only a small part can here be presented. For discussion 

 I have selected two places, namely one typical woodland pool where 

 continuous breeding of Aedes canadensis occurred and another where 

 supposedly no breeding would take place. 



"The first place was located about 200 feet from a highway (Union 

 Avenue) in Passaic County and was surrounded by white maple, red 

 maple, oak, a few birch and beech trees, some brush, and a dense growth 

 of cinnamon ferns. At the bottom of the pool was a mat of decaying 

 leaves. It was irregular in shape, fairly shallow, ranging from twelve to 

 eighteen inches deep, and about seventy feet long by forty feet wide. At 

 the end of May about ninety-five per cent of the pool was shaded at 

 noon tim*e, while at other times of the day the water surface was even 

 less exposed to the sun. 



"The second place, located in Union County, like number 43 along 

 Galloping Hill Road, had not bred mosquitoes for several years. This 

 pool was practically round, fifty feet in diameter, and from three to 

 five feet deep. It was shaded by red oaks and pin oaks on three sides, but 

 in the afternoon was exposed to the sun. In July the edges of the pond 

 were covered with duck weed and it was about half filled with water 

 lilies. There was some surface drainage from the concrete road. At the 

 end of July some old iron and tin cans were noticed, in addition to the 

 dead wood earlier present. 



"Tables V and VI show the results for the Passaic County pool. It 

 will be noticed that the food supply was abundant throughout the sum- 

 mer. The water remained acid with some variations. Chlorides were low, 

 except in the middle of June when the water became low. At this time 

 larvae disappeared entirely. After the pool had been dry for six weeks, 

 heavy rains brought back water and a few days later breeding was very 

 heavy again. However, the water disappeared rapidly and no water was 

 reported for the remainder of the season. Our samples were taken in 

 duplicate, one for microscopic and chemical examination, the other for 

 larvae. Early in the season an attempt was made to find out what the 

 larvae eat by examining the water in both bottles, but this might be 

 considered as not being representative, since they would possibly take 

 anything they could get in such a relatively small amount of water. 



