92 N. J. Mosquito Extermination Association 



systems in operation for a number of years. And in many cases 

 some of these factors were not evaluated, with the result that the 

 data were not reliable. 



Now take the case of the principal malaria mosquito, that is, 

 the quadrimaculatus. Under ordinary evening collection you get 

 practically none whatever unless you are close to a place of breeding. 

 That has been met evidently in the south by collecting in buildings, 

 around buildings where they gather. 



Now in the Princeton anti-malarial work we found that our col- 

 lectors in ordinary evening collections in bunches of shrubbery got 

 no specimens of quadrimaculatus whatever unless they were close to 

 the place of breeding. At the same time a mile away, in the village 

 of Princeton, considerable numbers of the quadrimaculatus would be 

 caught inside the houses, and yet no breeding of quadrimaculatus 

 could be found in the immediate territory adjacent to those places. 

 It was evident, judging from the breeding then, that they had trav- 

 eled nearly a mile, in many cases, to get to these houses. So you 

 see ordinary evening collection work will not answer for the 

 quadrimaculatus. 



In the case of the pipiens the evening collection is very success- 

 ful. But again these factors I mention must be evaluated. You 

 may collect on a street corner in a certain portion of Montclair, 

 we will say, and get no pipiens whatever. You may step one hun- 

 dred and fifty feet back into the backyard, where the shrubbery is, 

 and you may catch one pipiens a minute. 



Now we have evaluated the time factor; we have used that for a 

 number of years. We count that when a collector is getting thirty 

 mosquitoes in five minutes his further collection is limited by his 

 speed of collection. We count that when we get a mosquito a 

 minute we have got a serious infestation that needs immediate look- 

 ing to. 



Another thing is the question of your cyanide or killing tubes. 

 Every inspector has to have at least two tubes, so that while the 

 mosquito which is caught is dying in that tube he has got another 

 tube to catch with. And if his tubes are not very active he has 

 got to have three tubes, and so on. 



Now we have used this method of collection to determine the 

 density of the mosquito fauna and we have used that to determine 

 the movements of mosquitoes, the migrations of mosquitoes. We 

 have used it to determine the appearance of mosquitoes from un- 



