iOO 



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



Num- 



Number 

 of fe- 

 males. 



Period. 



Average 

 effective 

 tempera- 

 ture. 



Total. 



Daily average. 



Average per 

 weevil daCy. 



ber of 

 males. 



Feeding 

 punc- 

 tures. 



Eggs. 



Feeding 

 punc- 

 tures. 



Eggs. 



Feeding 

 punc- 

 tures. 



Eggs. 



10 



10 

 10 

 10 

 10 



1903. 

 June 6 to 30 



°F. 

 32.1 

 36.5 

 32.7 

 24.6 



2,189 



2,325 



1,540 



900 



794 



1,061 



659 



217 



87.6 

 93.0 

 61.6 

 36.0 



31.8 



42.4 



26.4 



8.7 



4.4 

 4.7 

 3.1 

 1.8 



3 2 



10 

 10 

 10 



July25toAug.l9.... 



Sept. 14 to Oct. 8 



Nov. 3 to 27 



4.2 

 2.6 

 0.9 









The average number of daily feeding punctures is reckoned for both 

 sexes alike. Though the females made more than half, the propor- 

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

 if it could be done. It is noticeable that the period of greatest activ- 

 ity 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 eating 

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



INFLUENCE OF RETABDEB DEVEI^OPMENT UPON SEX. 



For these experiments five lots of selected infested squares were 

 picked from plants in the field. In most cases the eggs had been 

 deposited long enough for warts to become fully developed; in other 

 cases the squares showed egg punctures which had been made so 

 recently that warts had not 3^et formed. The age of the infestation at 

 the time the squares were picked ranged, therefore, probably between 

 two and six days. These infested squares were kept at a low temperature 

 in the ice box especially constructed for the purpose. Two lots were 

 kept at about 45° F. during the night, but removed to ordinary out- 

 door temperatures during the daytime, cold and warm thus alternating. 

 Three lots were kept continuously at a temperature ranging between 

 62° and 70° F. The checks upon these experiments were all kept at 

 ordinary outdoor temperatures. The plan was to determine each day 

 the sex of such weevils as emerged. From the check lots of squares 

 36.4 per cent of the wxevils emerging were males, and these required 

 upon an average a total effective temperature of 588.8°. The 63.6 per 

 cent of females required an average total effective temperature of 587°. 

 The results of the tests are shown in the table on page 101. 



