96 



possible for two generations to span the entire year. Tiie weevils 

 developing after the middle of November may go into hibernation, and 

 from their last-deposited eggs produce weevils whose last offspring 

 will be ready for successful hibernation again. This conclusion is 

 based upon actual demonstration. 



The maximum number of generations will be found by taking the 

 first, instead of the last, deposited eggs in each case. Rather than lay 

 the conclusions open to question by taking the figures found for occa 

 sional minimum length of the life cycle, we will take the 25-day 

 period, which has been shown to be the average between June 4 and 

 November 16. Without doubt hibernated females begin their repro- 

 ductive activity in average seasons by May 1 in the locality of Vic- 

 toria, and their descendants continue to develop normally until after 

 November 15. Taking the dates mentioned, however, as the average 

 season for the weevils, we find that eight generations, each having the 

 average period of development, may usually be produced within the 

 year. 



In determining the average number of generations one-third" the 

 average period of oviposition should be added to the average life cycle 

 for each generation. As it has been found that the average period of 

 oviposition is about 55i days, we must allow 25 days for the develop- 

 ment of the average adult and 18 more days for the female to deposit 

 one-half her eggs. Forty -three days is therefore about the average 

 length of a generation; and we may thus count on an average of about 

 five generations between May 1 and December 1. In the northern 

 part of the weevil territory, where the season is shorter and the pre- 

 vailing temperature lower, probably only four average generations are 

 developed. This theoretical conclusion is fully confirmed by the 

 results of breeding experiments conducted at Victoria and Terrell dur- 

 ing the season of 1901. 



There is no basis for the idea that there is a distinct hibernation 

 brood. The activity of the adults and the development of the imma- 

 ture stages is gradually retarded by the decline in temperature until 

 hibernation time arrives. Most of the weevils of the first two or three 

 generations have probably died, or then do so, while most of the adults 

 of later generations, having still considerable vitality, will go into 

 hibernation. It is certain that every generation preceding may have 

 some direct part in the production of weevils which shall hibernate. 

 All weevils which are still strong and healthy when cold weather comes 

 on may be expected to go into hibernation, so that there can be no 

 special brood for this purpose. 



« One-third is nearer the correct fraction than one-half, since it has been found 

 that Aveevils deposit considerably more than one-half of their eggs during the first 

 half of their oviposition period. 



