24 N. J. Mosquito Extermination Association 



to find is a report by Lenz on malaria in a region free from this 

 disease, namely in the prisoners' camp at Puchheim. 



The amount of intelligence and ingenuity exerted and the exact 

 scientific information upon which measures were based before the 

 war is shown by the rather surprising paucity of new ideas of prac- 

 tical value which came to the front during the war. I have referred 

 in previous paragraphs to Wrightson's larvicide used at Tampico ; 

 to fish culture as alleviating conditions in rice fields in Trinidad ; to 

 the sowing of surface algae over the surface of certain pools in 

 Sardinia, and to the concentration of larvae in specially prepared 

 traps in Zanzibar. Aside from this, it will be of interest to call 

 attention to certain additional ideas which have been noted. 



In 191 3 an important note was published by F. Knab on the con- 

 trol of northern mosquitoes, in which he stated that "The bulk of 

 the mosquitoes of North America are derived from larvae which 

 develop in snow-water in early spring, and for a short period all 

 the lesser bodies of water swarm with larvae though none can be 

 found in them during the remainder of the season." I think Knab 

 was in error in his statement that the bulk of the mosquitos of North 

 America are so derived, but the observation is of great importance 

 as applying to the bulk of the mosquitoes of the more northern 

 states, not only those of the wooded regions in northern New Eng- 

 land, New York, Wisconsin and Michigan, but those of the prairie 

 regions in the northern states farther west. Knab called attention 

 to the suggestion of Dr. A. Eysell that the removal and burning 

 late in the autumn of the old dead leaves and plant debris from 

 the dried-out pools in which the larvae would appear later is likely 

 to be thoroughly effective if properly carried out. 



Acting upon this method of breeding of the more northern mos- 

 quitoes, I was able to do some moderately effective work during two 

 consecutive years in Greene County, New York, by a thorough oil- 

 ing, during April, of the snow-water pools in which larvae were 

 to be found in great numbers. Since the mosquitoes which issue in 

 late April and May from these snow-water pools persist until July 

 and sometimes until August, eventually laying their eggs in hollows 

 which will be filled the following spring by melting snow-water, 

 some method of control becomes very important to many of the 

 northern woodland summer resorts. My experience has shown that 

 perfect results from the oiling method tried are very difficult to 

 reach, since these woodland pools, in addition to being fugitive, ar.^ 



