BIOLOGY OF THE MEXICAN COTTON BOLL WEEVIL. 



35 



in the trees were supplied with moss only and averaged 10 feet above 

 the surface of the ground (fig. 15). 



The boll weevils were collected from near-by cotton fields and in- 

 stalled in the cages every two weeks, beginning on October 1, the last 

 cages being installed on December 1. 



TIME OF ENTRANCE INTO HIBERNATION. 



The time of entrance into hibernation by the boll weevil at Madi- 

 son, Fla., usually begins about the time of the first killing frost. 



The average date of this event is November 29. 



During the fall of 



Fig. 14. — Hibernation cages in the open field at Madison, Fla. 



1918, however, the warm weather held on until about December 8. 

 On November 13 the temperature dropped to 37° F., but the 20 days 

 following this drop were extremely warm and all weevils seemed 

 active until the drop in temperature on December 8. The weevils 

 were in hibernation almost continuously until February 20, the date 

 on which the emergence records were started. The mean tempera- 

 ture for November was 59.1° F. and 56.4° F. for December. When 

 it is considered that hibernation begins between mean temperatures 

 of 56 and 60° F. it is seen that the hibernation of the weevil in 

 Florida during November and December is more of a drowsy con- 

 dition than one of inactivity. The mean temperature for January, 



1919, was 46.6° F. and for February 61.9° F. Therefore the weevil 

 really entered hibernation late in December and remained in this 

 condition for the month of January. 



