Proceedings of the Section of Biology 229 



Mr. Charles- W. Leng, President of the New York Ento- 

 mological Society, then assumed the chair, and Professor John B. 

 Smith gave a lecture, illustrated by the stereopticon, on The 

 Mosquito Problem. 



A test count of mosquito larvae in a small pond warranted an 

 estimate that " in 20,000 square feet of water there were 10,600,- 

 000 " wrigglers. These mosquitoes produced six to eight broods 

 annually. The exterminations of this menace to health cost $35. 



The dense swamps in forests are seldom breeding places. A 

 pond covered with duck weed or other heavy vegetation gives the 

 enemy little breathing place. The Anopheles, the malaria carrier, 

 prefers semi-open water with sandy sloping banks. In towns 

 the worst haunts are in casual pools, or various bodies of water 

 artificially created. A trolley road to Coney Island, by cutting 

 off the water ways beneath the track, has created an enormous 

 area of ideal breeding places. The open village gutter where the 

 water can collect is a menace of the first importance. 



For the great area of salt marsh the only remedy is draining. 

 So far, about 3,000,000 feet of drainage ditch have been dug in 

 New Jersey. The work on Staten Island has made very good 

 progress, thanks entirely to health officer Doty. 



Ditches were formerly dug about 18 inches deep. These filled. 

 The new ditch is three feet deep. The section of excavation 

 shows that the upper half is a mass of roots. In after years the 

 upper half of the ditch tends to close somewhat, leaving a clear 

 drain beneath. The ditch drains satisfactorily about 100 feet on 

 either side. Of course the ditch must have a mouth in open 

 water, They occasionally have to be 2,000 feet long. 



In one instance, where an outlet was distant, satisfactory 

 results were obtained by centering the ditches at a large excava- 

 tion dug down until the water was influenced by the tide. This 

 was kept stocked with " killies," which would thrive well were 

 it not for the depredations of the turtles. As it is, the pool is 

 stocked each year at trifling expense. 



Instance after instance can be cited where land held almost 



