1916 ENTOMOLOGICAL SOCIETY. 131 



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Further 1 may say that up to the present we have little information in this 

 Province on the habits of this fly and little knowledge, other than the generally 

 accepted conceptions, on which to base the more approved remedial measures. . 



Without entering upon a detailed study of the complete life history of the fly, 

 I wish to say that usually there are three complete and overlapping generations of 

 this Hy at Agassiz. It is possible for forms of the third generation to appear on 

 the plants as early as July 18th, developing from the first eggs of each generation, 

 while the second generation would ordinarily cease approximately about Sept- 

 ember 1st. 



I will commence the discussion on the autumn development of this fly from 

 this date, September 1st, and, in doing so, consequently, we will be dealing in all 

 probability with third generation forms with a possibility that certain of the 

 younger stages may belong to the fourth generation. 



Autumn Fly Emergence, 



Cabbages and cauliflowers are harvested mainly in the months of August and 

 September. During the past three years larvae have been observed at times during 

 each of the months of October, November and December working on roots of 

 cruciferous plants. This year particularly an attempt was made to account for 

 these larvae and to solve the question of the hibernating form, 



In the process of harvesting, therefore, collection was made of all pupae seen 

 and these were placed under observation in a sheltered place, but under supposedly 

 equal atmospheric conditions as would prevail in the open field. One was struck 

 during the course of the field observations with the preponderance of pupal forms 

 over the larval, and one might easily suppose that given a cold wet autumn with 

 low maximum and minimum temperatures that pupal forms would continue as 

 such for the winter and larvae would complete their growth and pass the winter as 

 pupae also. Detailed observations in an autumn of such a nature are lacking up 

 till the present. As it happened, the past two years, 1914, 1915, when the notes 

 herein presented were recorded, have been open and mild, during September and 

 October. Such a condition is not out of the ordinary in this part of the world, 

 thus the facts recorded are of interest. 



From puparia collected, therefore, the following emergence of flies is re- 

 corded. It will be seen that the number of puparia under observation is increased 

 on certain days. This is explained by the fact that harvesting operations were 

 coiitinuiiiu- and more pupte were being collected and added to the number under 



observation. 



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