30 HIBERNATION OF THE COTTON BOLL WEEVIL. 



temperatures and departures from normal. The records for February 

 are especially significant. In 1905 this month was unusually cold 

 throughout the State. The absolute minimum for the five local- 

 ities considered in that year was 2° F. at Dallas and the average mini- 

 mum was 8.3° F. below that occurring in 1906. In 1905 the mean 

 average temperature for the month Avas 10.6° F. below the normal 

 while in 1906 it was but 0.12° F. below normal. It was during this 

 month of extreme cold with excessive rainfall in 1905 that the great- 

 est mortality among wee^nl stages occurred. 



HIBERNATION SHELTER OTHER THAN BOLLS WITHIN THE FIELD. 



During an ordinary season it can not be doubted that a large 

 majority of the weevils whicli survive find some other shelter than 

 the bolls hanging upon the plants. It is not, however, as easy a 

 matter to find weevils in rubbish scattered upon the ground as in 

 bolls. It is necessary to collect the rubbish very carefully and sift 

 it over cloth or paper to separate the weevils from the trash. In 

 this way it has been found that weevils hibernate extensivel}^ in the 

 leaf and grass rubbish distributed throughout the field. Naturally 

 the cleaner the field in the fall the smaller will be their chances of 

 finding favorable shelter during the winter. 



Standing trees are a common sight in cotton fields'^ and while the 

 records of weevils found hibernating under bark are but few they 

 are sufficient to indicate that these trees may be a rather important 

 factor where they occur in considerable numbers. Where the 

 Spanish moss (Tillandsia usneoides) (PI. II, fig. 1) occurs, as in the 

 bottom lands in the coast section of Texas and in the southern por- 

 tions of the Gulf States, w^eevils find exceptionally favorable shelter 

 within this moss. On January 18 Mr. J. D. jMitchell cut down a 

 moss-covered tree growing in a large cotton field in the vicinity of 

 Victoria, Tex. Between 400 and 500 pounds of moss growing on 

 this tree was collected and examined very carefully. Three living 

 specimens of the boll weevil were found. On February 5, 1907, a 

 similar experiment was tried. One thousand pounds of moss was 

 obtained from a tree standing in the midst of cotton fields. The 

 moss was situated from 7 to 15 feet above the ground. Among a 

 large number of other insects found hibernating in the moss there 

 were ten living boll weevils. The weevils seem to prefer the festoons 

 of green hanging moss to the bunches of dead matted moss (PI. II, 

 fig. 2). 



The turnrows and ditches throughout the fields and the fence rows 

 (PI. I, fig. 2) surrounding them present exceptionally favorable con- 

 ditions for successful hibernation. It has been noticed frequently 

 that early in the season the most severe injury may occur on the 

 edge of a field adjoining a fence row where weeds and grass abound. 



