13S JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



To sura up, there were three effective broods of this insect in 1909 

 while during the summer of 1911 there was only one brood of insects 

 present in sufficient numbers to be of economic importance. In west- 

 ern New York there are two periods each year when adults can be found 

 about cabbage plants— in the spring, and in the fall. The spring adults 

 come largely from the autumn brood of larva), though some flies are 

 from delayed pupse of the first and second generation of the previous 

 season. The adults found in the autumn are from both first and 

 second brood pupae. 



President Glenn W. Herrick: Is there any discussion? 



Mr. T. J. Headlee: I should like to ask to what general cause 

 the speaker ascribes this retardation. 



Mr. W. J. Schoene: After observing this insect for eight seasons, 

 we have decided that the insect thrives best in a cold moist climate. 

 The normal summer weather in Western New York is unfavorable to 

 the species and, like some other insects, it remains dormant during the 

 summer period. 



Mr. T. J. Headlee: I would like to ask whether moisture plays a 

 part. 



Mr. W. J. Schoene: Moisture and temperature are very closely 

 related and it is difficult to separate the influence of these conditions. 

 Judging from some experiments out of doors, moisture had little to do 

 in causing this delay and certainly has no effect after the larva pupates. 



Mr. W. C. O'Kane: This question of delay of individuals brings 

 to mind the life-history of the apple maggot: We found a part of the 

 individuals of that species leaving the pupal stage the second summer 

 instead of the first summer. These irregularities occurred with groups 

 of individuals, all of which so far as human measurements could 

 determine, had the same physical surroundings. This appeared to be 

 a characteristic of the species, as much a part of its nature as any of 

 its obvious physical characteristics. In effect it provided against the 

 serious results to the species that would otherwise follow non-fruiting 

 of apple trees in large areas. 



Mr. T. J. Headlee: It seems probable from the results of the 

 work in other biological lines that activities of an organism incident 

 to an inherited physical or chemical structure are initated by stimuli 

 arising from its environment and that these stimuli can be found and 

 measured. 



Regarding the impracticabihty of separating the effects of tempera- 

 ture and moisture, I desire to say that my experience indicates that 

 the operation is one which requires proper machinery. 



