THE BOLL WEEVIL PROBLEM. 29 
the Bureau of Entomology during the season of 1908. It was 
learned that some planters in the Red River Valley below Shreve- 
port, La., were making fair crops (in one case 600 bales on 900 
acres), while others were making very small yields, as, for instance, 
in one case 200 bales on 800 acres. Upon investigation it was found 
that all the planters in the neighborhood were compelled to put all 
their hands on levee work for five weeks to save their places. Dur- 
ing that time the cotton remained uncultivated. After the subsid- 
ence of the flood the fields were plowed. Where this work was done 
carefully good crops were being produced. In cases where the plows 
were run too deeply and too close to the plants excessive shedding 
had taken place and the weevils prevented the putting on of any more 
fruit. Careful investigation on several places where the essential con- 
ditions were identical left no doubt that the cause of the difference in 
yields was primarily the difference in summer cultivation. 
Occasionally a farmer is found who has obtained better yields on 
fields where cultivation has been discontinued early. In fact, the 
writer has seen fields full of grass that. were outyielding perfectly 
clean ones on the same plantation. Such situations have caused 
erroneous conclusions. As a matter of fact, the explanation is that 
the late, careless cultivations had done more harm than good. The 
importance of careful shallow summer cultivations can not be too 
strongly emphasized. 
SPECIAL DEVICES FOR DESTROYING WEEVILS. 
The impression is more or less general that the only important way 
in which weevils may be killed is by the removal of the infested 
plants and that all other steps in the system of control are merely to 
avoid damage by the weevils that have survived that destruction, and 
their offspring. In spite of this impression, however, it is urged that 
the destruction of myriads of weevils can be accomplished during the 
growing season. This is to be done by working in cooperation with 
the natural agencies that destroy the weevil. 
In making examinations of many thousands of infested squares 
from different localities and different, situations in cotton fields it 
was found that mortality was conspicuously greatest where the sun- 
light was least obstructed and the heat, consequently, the greatest. 
The mortality in infested squares in the middles was many times 
as great as in the case of squares which remained under the shade of 
the branches. The temperature at the surface of the ground during 
warm days runs considerably higher than at a few feet above the sur- 
face. For instance, it was found that when the temperature was 
100° F. in the reguiar Weather Bureau shelter about 4 feet above the 
512 
