N. J. Mosquito Extermination Association 51 



perature of approximately 80 degrees F is most favorable to the 

 mosquito activity, a temperature of 60 degrees F or below and a 

 temperature of 95 degrees F or above renders them relatively 

 inactive. Furthermore, it is also known that heavy plant growth 

 forms a harbor or shelter for most of the species, and that collec- 

 tions taken in localities where growth of this sort exists will catch 

 a far larger number of mosquitoes than where it does not exist. 

 The variable of elevation seems to operate mainly through air 

 movements, temperatures and moistures, and the conditions of 

 these factors which are most favorable hold at various elevations. 

 Most mosquitoes are negatively phototropic to strong light and 

 positively phototropic to weak light, consequently mosquitoes are 

 less active during the day and also less active during night than 

 they are at that period of the 24 hours when the day is passing 

 into night. The lower temperatures and that period when night 

 is passing into day are primarily responsible for the much reduced 

 activity of mosquitoes as compared with their activity at the cor- 

 responding period in the evening. The variable of the human 

 collector is probably the most difficult of all the variables to 

 handle, because the activity, the methods used and the attractive- 

 ness of the individual collector has at least as many variations as 

 the number of collectors employed. 



conditions under which coIvIvEctions must be made ii^ 

 resui.ts are to be reuabive. 



All things considered on the basis of the conditions set forth in 

 the preceding paragraph, it would seem that the method of deter- 

 mining mosquito density over an area of country is best served 

 by making mosquito collections in the largest practicable number 

 of stations within the limited period at the same hour of the 

 evening, in places which, from the standpoint of plant growth, 

 wind movement, light and atmospheric moisture, are primarily 

 the same ; nor does it by any means seem impracticable to secure 

 localities that are very similar in these respects. 



The elimination of the three variables mentioned in relation to 

 the collector is a much more difficult matter, and it is only by 

 utilizing a carefully selected and trained body of men, whose 

 differences in activity, methods and attractiveness as bait have 

 been evaluated, that a reliable result in the way of mosquito col- 

 lections can be obtained. In practice in this state there are very 

 few, if any, instances in which the conditions just specified have 

 been complied with. Lack of understanding of the requirements 

 for successful collections and scarcity of collectors have been 

 primarily responsible for this failure to meet the necessary condi- 



