LONGEVITY OF WEEVILS AFTER EMERGENCE. 83 



LONGEVITY OF WEEVILS AFTER EMERGENCE FROM 

 HIBERNATION. 



Preceding records have shown that on the average the weevils sur- 

 viving hibernation had Hved for over five months before their emer- 

 gence. It is impossible to determine even approximately how old 

 weevils may have been at the time they were placed in the hiberna- 

 tion cages. The longevity records here shown must, therefore, be 

 ver}^ conservative. They may indicate very closely the average 

 length of life of weevils which survive hibernation, but shoultl not be 

 considered as showing actually the maximum longevity. It has 

 seemed advisable, therefore, to base the studies upon longevity after 

 emergence from hibernation, since the exact dates for emergence and 

 for deaths have been carefully determined. 



As the weevils were collected daily from the cages, those found at 

 each date must have emerged practically upon that date. It was 

 the general practice to divide the weevils from each section of the 

 cage into two lots of approximately equal numbers, one lot being 

 placed in a series in which they received no food and the second lot 

 being placed in a series which was supplied whatever stage of cotton 

 was then available to weevils in the field where the experiments were 

 being made. Thus, early in the season at Dallas, all weevils were 

 necessarily placed in unfed series, since no cotton existed in the field. 

 In each locality the first food consisted of the tender leaves of volun- 

 teer or sprout plants. As soon as squares were formed in the field 

 these were supplied to the weevils in the fed series of experiments. 



As a general rule the weevils emerging upon three consecutive 

 days were placed in a cage bearing the same series designation, and 

 the average date of emergence was considered as applying to the 

 entire lot. This arrangement was necessary to reduce the amount of 

 work required in caring for so many cages as would be needed to 

 keep each day's weevils entirely separate. 



In both the fed and unfed series frequent examinations were made 

 to determine the time of death of each weevil, and fresh food was 

 supplied to weevils in the fed series. Upon the death of a weevil 

 its sex was determined and its period of life after emergence was also 

 recorded. The manner in which sex can be positively determined is 

 described in succeeding paragraphs. (See p. 91.) In this way the 

 records for each lot bearing a serial number were kept by themselves 

 and the results for each series are comparable with all others. While 

 it would be most significant to present the records in the form of a 

 summary of each series which would allow these comparisons to be 

 seen, the necessity for abridging the tabular matter, so far as may be 

 possible, prevents our doing so. Therefore for both the "unfed" 

 and for the "fed" experiments we can give only the grand totals 

 and averages with general statements based upon the tabular studies 

 from which these figures are obtained. 



