LONGEVITY OF WEEVILS AFTER EMERGENCE. 89 



At Dallas the number of weevils surviving for two months or 

 more amounted to 15.6 per cent of the total number observed. Prac- 

 tically 50 per cent of each sex survived for more than six weeks. 



At Calvert 15 per cent of the total number of weevils survived 

 over fifty days and 50 per cent for more than thirty days. The 

 average life at Calvert was nearly ten days less than at Dallas. It 

 is very noticeable that those weevils which lived longest at Calvert 

 emerged during about the middle of the emergence period. The 

 weevils which were very late in emerging survived for only a short 

 time. The decrease in the percentage of survival is markedly regular 

 from the first ten days to the end of the period. The most decided 

 decrease occurs between sixty and seventy days. 



The maximum longevity at Victoria fell considerably short of 

 that at Calvert and Dallas. In this case 15 per cent of the weevils 

 survived beyond only about twenty-five days and nearly 50 per 

 cent died during the first ten days. The reason for the marked 

 shortening of life at Victoria was undoubtedly the greater exposure 

 to sunshine of the jars in which the weevils were confined. 



This comparison shows that length of life uniformly averages 

 longer in northern Texas than in either central or southern Texas. 

 At Dallas 3 weevils, at Calvert 1, and at Victoria none lived more 

 than one hundred days. At Dallas 11 weevils, at Calvert 5, and at 

 Victoria none lived more than ninety days. From the grand sum- 

 mary of the records in both sexes it appears that among approxi- 

 mately 3,000 weevils 50 per cent died during the first twenty days. 

 Two-thirds of them died in the first thirty days and three-fourths of 

 them in the first forty days. 



From these records it appears that any kind of a food supply will 

 serve to maintain a majority of the emerging weevils for more than 

 three weeks. This consideration has a special significance in southern 

 Texas, where sprout and volunteer cotton usually occur. This sub- 

 ject will be further considered in the relation of hibernated weevils 

 to food supply. 



BEARING OF OBSERVATIONS ON FED AND UNFED WEEVILS ON THE 

 POSSIBILITY OF AVOIDING DAMAGE TO COTTON BY LATE PLANTING. 



One of the most important features of the experiments on the long- 

 evity, with and without food, of weevils that have survived the 

 winter, is the bearing that the results have on the theory of late 

 planting of cotton to avoid damage. This theory has been pro- 

 pounded by numerous persons ever since 1895. 



In the series of experiments with unfed weevils 4,600 individuals 

 were used; in the series with fed weevils 2,965. The unfed series is 

 the more important with reference to late planting, The maximum 

 length of life of the unfed weevils emerging in February, 1907, was 



