BIOLOGY OF THE MEXICAN COTTON BOLL WEEVIL. 



19 



reading on the seventh day gave 84° on the soil and 87° above the 

 soil in the tumblers. On the twelfth day the temperature was 84° on 

 the soil and 86.5° above the soil. Thus, on this particular day, 

 weevils developing in 

 squares on the plant 

 were experiencing 

 88° F., or probably 

 less, and those in the 

 squares which had 

 fallen on the ground 

 were receiving from 

 92° to 115° F., ac- 

 cording to whether 

 they were shaded or 

 exposed to the sun, 

 while weevils in the 

 insectary were faring 

 well at 83.5° to 87° F. 

 It has been shown 

 that the most fa- 

 vorable temperature 

 for development is 

 between 83° and 

 84° F. 



In order completely 

 to check up condi- 

 tions maximum and 

 minimum thermome- 

 ters were installed 

 in the field hatch- 

 ery. Thus the maxi- 

 mum and minimum 

 temperatures experi- 

 enced by the weevils after the falling of the. infested square (fig. 9) 

 were measured. 



Fig. 9.- — Thermometers installed underneath the cotton 

 plants in the field to secure soil temperature, Madi- 

 son, Fla. 



EGG-LAYING ACTIVITY OF HIBERNATED FEMALE WEEVILS 

 UNDER FIELD CONDITIONS. 



Table IX gives the data on the egg-laying activities of female 

 weevils under field conditions on upland cotton squares. The females 

 deposited an average of 76 eggs each at a rate of 8.4 eggs per day. 

 The maximum number of eggs during any one day was 19. It is 

 practically impossible to keep a continuous record of female weevils 



