358 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 6 



point where the prediction is made. These points have to be worked 

 out locally and are of chief importance as indicating when the marsh 

 will be uncovered during periods of high tides, as work on them is 

 easier and more effective at that time. 



Although rainfall is a factor in the abundance of mosquitoes, it does 

 not necessarily follow that the more rain the more mosquitoes. So 

 far as salt marsh mosquitoes are concerned, the time and size of the 

 individual rains are of great importance. A rain storm occurring 

 when the tides almost reach the flood line may be sufficient to raise 

 the water level so that a brood is produced. At another period when 

 the tide level is low the same amount of rain might be carried off with- 

 out its first covering the marsh. As near as we can judge at present, 

 it takes a rainfall of at Least an inch within 24 hours to start a brood 

 of salt marsh mosquitoes, although rain in any amount, when larvae 

 are growing, will help to keep the pools from drying and increase the 

 size of the brood. Rain may at times actually prevent breeding. A 

 slight rain may cause the eggs to hatch but not provide water enough 

 for their full development, thus effectually destroying them. 



As is seen from the tables, after the first of June the rainfall at New 

 Haven for 1912 was below normal as well as below the precipitation 

 for 1911. 



RALNFALL AT NEW HAVEN, CONN., DURING MOSQUITO SEASON. 

 (From United States Weather Bureau) 



April 



May 



June 



July 



August 



September 



October (1st to 15th) 



4.31 

 0.74 

 2.73 

 2.17 

 5.57 

 2.33 

 2.12 



4.56 

 6.34 

 0.50 

 2.14 

 3.22 

 2.32 

 .11 



However, the rains in 1912 were largely at such times as to aggra- 

 vate mosquito breeding. Starting with April, there were heavy 

 rains about the 29th which increased the size of the second brood of 

 the season. On May 16, at the height of the perigee of that month, 

 it rained 2.85 inches. During June, not enough rain fell at any one 

 time to affect breeding conditions. On July 21, just as the last of 

 the July brood was emerging, we had nearly an inch of rain, which 

 served to provide enough water to allow the fag end of the brood to 



