136 



A comparison of the temperatures obtained at the surface of the 

 ground with those recorded in a shelter such as is used by the Weather 

 Bureau in obtaining all standard temperatures shows that at the surface 

 of the ground in the sun the temperature ranges between 20° and 30° 

 higher than the temperature recorded in the shade. The maximum 

 Weather Bureau temperature obtained for the period of the test was 

 94:° and ^4.5°, while the ground temperature reached the maximum of 

 119° or 120°. The examinations made at these temperatures showed 

 that they had produced practically no fatal effect upon the weevil larvae 

 and pupie, since it is reasonable to assume that a small percentage may 

 be expected to die even under the most normal conditions. 



At Victoria it not infrequently happens that the temperature in the 

 shade goes above 100°, though this temperature has not been reached 

 during the past two seasons. It seems very probable that when the 

 temperature in the shade reaches or goes above 100° F. the tempera- 

 ture at the surface of dry ground, especially if the soil be light and 

 sand}^, will be found to exceed 130°, and at that temperature a consid- 

 erable mortality among weevil stages in squares exposed to the sun 

 might reasonably be expected. It is probable that drought and dew 

 conditions will be found to be important factors in determining the 

 mortality in the sun. 



In July, 1901, at San Carlos, Coahuila, Mexico, Mr. A. F. Rangel, 

 in the course of observations and experiments which he made for Prof. 

 A. L. Herrera, recorded a mortality amounting to 75 per cent among 

 the larvae in squares fully exposed to sunshine during a severe drought, 

 while the temperature ranged from 104° to 117° F. at the surface of 

 the ground and in the sunshine. 



TEMPERATURE ENDURED BY WEEVIL STAGES IN WINTER. 



It is still an open question as to how low winter temperatures the 

 weevil can withstand. It is certain that in southern Texas many larvae 

 and pupae slowly continue their development during the winter season. 

 Mr. S. G. Borden, of Sharpsburg, Tex., in a letter written January 



27, 1896, says: 



Hands clearing up cotton stalks report plenty of the larvae in dry bolls. 



Mr. Schwarz found weevils hibernating in all stages, except the 

 egg. at Victoria, Tex., during February, 1902. At the same locality 

 in January and February of 1904, the weevils in larval, pupal, and 

 adult stages were taken alive from dry bolls by Mr. J. D. Mitchell, a 

 resident and cotton planter of that place. 



After the weevils first made their appearance at San Antonio in the 

 fall of 1895 they were supposed to have been entirely destroyed by 

 frosts during the following winter. The lowest temperature recorded 

 at San Antonio for that winter was 26° F. on December 30, 1895. 



