762 EXPEEIMENT STATION RECORD. 



those wliicli liave been active for a number of weeks before the time for them 

 to hibernate successfully. The duration of the entrance period for the species 

 depends upon the severity of the drop in temperature below about 43° F. of mean 

 average temperature. This period usually occurs coincidently with the first 

 killing frosts and extends through a period of about 25 days. Hibernation 

 usually takes place as the mean average temperature falls below 55° and may 

 remain complete until the mean temperature rises above 60°. Temperature con- 

 ditions were practically normal during November, 1906, and the most favor- 

 able time for entrance into hibernation was between November 12 and 15 at 

 Dallas, Tex., and slightly later at the more southern points. 



Shelter during hibernation is discussed at some length (pp. 25-33), the 

 following conclusions being drawn : Weevils may avail themselves of almost 

 any kind of shelter and the favorable character of the shelter in relation to the 

 prevailing climatic conditions will influence the percentage of survival. Many 

 pass the winter sheltered by the old bolls that remain hanging upon the stalks. 

 The percentage of survival in bolls decreases generally from southern to north- 

 ern Texas. Under exceptionally favorable climatic conditions the larvae which 

 are more than half grown may complete their development if in bolls and be- 

 come mature during the hibernation period. Immature stages in squares rarely 

 survive. 



Hibernation experiments in small cages (pp. 33-38), large cage experiments 

 at Keachie, La., and Dallas, Tex., in 1905-6 (pp. 38-52), emergence in the field 

 at Victoria, Tex., in 1906 (pp. 52-54), large cage experiments at Dallas, Cal- 

 vert, and Victoria, Tex., during 190(5-7 (pp. 55-94), and longevity of weevils 

 after emergence from hibernation (pp. 83-90), etc., are reported accompanied by 

 details in tabular form. 



In regard to weevil survival, the authors report exceptionally cold and wet 

 winter weather as most unfavorable for weevil survival. During the winter 

 of 1902-3, at Victoria, Tex., in the small cage experiments, with 356 weevils, 

 an average of about 11 per cent survived. During the following season, also at 

 Victoria, among 400 weevils, i of 1 per cent survived. During the winter of 

 1904-5, large numbers of weevils were under observation at each of 6 localities 

 ranging from the southern to the northern portions of the infested area. As 

 this was the season of most exceptional rainfall and cold, it was not surprising 

 that no weevil survived in the cage tests except at Victoria, which was the 

 most southern point of experiment. An average for the 6 localities shows a 

 survival of less than two-thirds of 1 per cent. In the small cage work of 

 1905-6, there was an average survival of 1.3 per cent, and practically all of this 

 occurred in the outdoor cages. In 3 localities under observation during 1906-7, 

 an average of 11.5 per cent of the 75,000 weevils placed in the experiments 

 survived and emerged. The average survival in each of the localities was as 

 follows: Calvert, 9.49 per cent, Dallas, 11.22 per cent, and Victoria, 13.47 per 

 cent. Occasionally weevils may survive in stored cotton seed and be distrib- 

 uted along with it at planting time. 



It has been found to be of common occurrence for the weevils to leave their 

 winter quarters upon warm days in spring, returning again to a condition of 

 inactivity for a period of several days or even weeks. The disappearance and 

 reappearance in the case of plainly marked individuals has been observed to 

 occur as many as 8 times and a maximum period of 43 days between appear- 

 ances has been recorded. In 1907^ emergence began during the last week or 

 10 days of February. At Dallas, 7.8 per cent, at Calvert, 10.5 per cent, and at 

 Victoria, 27.7 per cent of the total numbers of weevils placed in cages were 

 counted as being active at some time during the winter season when they should 

 normally have all been in complete hibernation. Very few weevils emerged 



