10 CONTROL OF THE BOLL WEEVIL. 
to force the development of fruit on the plants when the weevils are 
being held in check by the temperatures of the spring months. The 
ability of the cotton plant to grow during April and May is much 
greater than that of the weevils. This gives a margin of which the 
planter can take advantage. 
It has been proposed at various times that late planting would be 
of advantage in the fight against the weevil, but exhaustive tests 
made by the Bureau of Entomology and the Louisiana Crop-Pest 
Commission have demonstrated the fallacy of this proposal. 
In the section dealing with natural control it was shown that cli- 
matic checks are the most important that the boll weevil experi- 
ences. The principal manner in which climatic factors affect the 
weevil is through the drying of the fruit. Naturally, the more heat 
and light there is to reach the fallen squares the greater will be the 
effectiveness of the most important natural means of control. This 
is the basis for the recommendation that the plants should be given 
considerable space not only between the rows, but in the drill. Of 
course, it would be possible to place the plants entirely too far apart, 
and thus reduce the yield. There is a happy medium, however, at 
which planters must arrive from experience on their individual 
places. At the same time varieties should be cultivated which have 
a minimum tendency toward the formation of leafage. 
The work of the insect enemies of the boll weevil is increasing 
from year to year. This work should be encouraged so far as possi- — 
ble. It happens that several of the recommendations made for 
other reasons will result in facilitating the work of the enemies of the 
weevil. This is the case with early planting, wide spacing, and the 
use of varieties with sparse rather than dense leafage. Even the 
fall destruction of the stalks is not a disadvantage, because it forces 
the parasites at the end of the active season to native hosts that 
carry them through the winter. Wherever possible varieties should 
be planted which retain a large proportion of the infested squares, 
because the hanging squares are more favorable for parasite attack 
than those which fall. 
Whenever the squares are picked by hand they should, if practicable, 
be placed in screened cages, rather than burned or buried. In this 
way the weevils will be destroyed while the parasites may escape. 
The screen used on such cages should have meshes at the rate of 
about 14 to the inch. 
Numerous experiments have shown that a large proportion of the 
weevils buried under 2 inches of moist soil can not reach the sur- 
face. Unfortunately, it is not possible to plow the infested squares 
under 2 inches of soil during the growing season. The operation 
would result in injury to the root system and cause great shedding. 
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