79 



ture is ascending from 3l'° F. it must attain a liiglicr point to start 

 weevils into activity than tliat at which the same weevil will cease 

 activity when the mercury is going down. 



The observations upon the length of the entire developmental period 

 were made upon a different series of weevils. As is clearly shown in 

 the summary given in the latter part of the table, the sum of the 

 average lengths of the three stages agrees remarkably closely with 

 the length of the entire period as found in the 752 cases observed. 

 This close agreement, reached by entirely different methods, indicates 

 that the series from which the averages are obtained are sufficiently 

 large to give constant results, and therefore that the average period 

 of development throughout the season of weevil activity is very close 

 to 18 days. 



This thermal influence upon activity in feeding and oviposition may 

 be shown by taking various lots of weevils at intervals through the 

 season. For this purpose the work of 10 males and 10 females has 

 been selected, using the laboratory records for each lot. The time 

 covered is 25 days in each case to secure a fair average, and 25-day 

 intervals separate the lots from each other. The season thus covered 

 begins with June G and ends with November 28, 1!)03. To make the 

 comparison fair, average conditions as to sex, age, and individual 

 activity must be established, and the records have been selected with 

 these conditions in view. 



Table XXI. — Thermal influence on activity in feeding and ovipositing. 



The average number of daily feeding punctures is reckoned for both 

 sexes alike. Though the females made more than half, the proj^or- 

 tions can not be positively separated, and it would make no difference 

 if Ave could do so. It is noticeable that the period of greatest activity 

 comes in midsummer, with the first, second, and third generations 

 actively at work. Hibernated weevils working in June show greater 

 activity than do the mixed generations which occur together in Septem- 

 ber and October, though the temperature does not greatly vary. In 

 November, with a marked fall in temperature, there is a corresponding 

 decrease in work, but especially is this noticeable in egg deposition. 

 It appears that at this season and later on the weevils are mostly eat- 

 ing to live until it becomes cold enough for them to hibernate. 



