21G Afinals Entomological Society of America [Vol. X, 



In 1913 the success in tracing the salt marsh species lead to 

 an attempt to trace the house mosquito which exhibited marked 

 concentration in certain areas within which and in the vicinity 

 of which no serious breeding of the species could be found. 

 Daylight collections promptly proved inadequate because the 

 house species would not readily attack the collector. Resort 

 was then had to evening collections, but the variations in time 

 required for one collector to cover the whole area seemed to 

 introduce a variable fatal to the result. To meet this difficulty 

 a number of collectors were employed along two lines of col- 

 lection running through the mosquito zone at right angles to 

 each other. Enough men were employed that the entire 

 collection could be secured within the limits of 13/2 hours. 

 By this means the collections were found to bear an under- 

 standable relation to each other, and by following the directions 

 of increasing density the source of breeding has been found. In 

 this way a zone of house mosquitoes originating in a sewage 

 charged salt marsh has been found which extended a distance 

 of 21/2 miles from the place of origin. 



The fact that nearly all species were taken in these evening 

 collections led the senior author to wonder whether the process 

 might not be used to determine the density of the mosquito 

 fauna throughout the protected area and thereby check up 

 the efficiency of the control work and point out the places 

 where greater effort was needed. 



In 1914 he had an opportunity to try out the matter in 

 Passaic County with the efficient assistance of Mr. David Young. 

 He found that not only did the method seem to show up the 

 efficiency of the control work, but served to demonstrate 

 the inefficiencies in time to permit their correction before the 

 householder was seriously troubled. The study seemed to 

 show that there existed a mosquito fauna of such an attenuated 

 character that the householder did not realize its existence 

 and that variation in it could be determined in time to head 

 off a really dangerous increase in number. 



In 1915 the evening collection became a part of the regular 

 mosquito control work in Essex, Passaic and Union Counties and 

 in 1916 it was employed in Bergen, Essex, Passaic, and Union and 

 utilized to some extent in Hudson, Middlesex, Monmouth, and 

 Atlantic Counties. It has enabled these counties to detect 

 promptly invasions from extra-territorial limits as well as incipi- 



