36 THE BOLL WEEVIL PROBLEM. 
increased the crop. In any case the topping of plants can probably 
do no harm in fields that are being damaged by the weevil. It is 
probable that the general results will be beneficial in causing the 
more rapid growth of the crop on the lower and middle branches. It 
has never been possible to demonstrate this in an exact way. Never- 
theless, for the general effects stated the topping of plants is included 
among the recommendations that should be followed, although as one 
of minor importance. 
COTTON LEAF-WORM AND BOLL WEEVIL. 
The relation between the formerly dreaded leaf-worm or so-called 
“army worm” (Alabama argillacea Hiibn.) and the boll weevil 
deserves special attention. A quarter of a century ago the efforts of 
entomologists and planters were directed toward some means of de- 
stroying the leaf-worm. The use of Paris green was found to be 
effective. Various changes in the general system of cropping cotton 
also caused the injuries to the leaf-worm to become less conspicuous 
year after year. Even up to the time of the spread of tlie weevil into 
Texas, however, poisoning was a more or less regular operation on all 
cotton farms. The insects never did any considerable damage before 
the middle or latter part of the season. The object in destroying the 
leaf-worm was that it prevented the maturity of a fall crop. For 
this reason the saving of the top crop and in exceptional seasons a 
part of the middle crop was all that was desired. The work of the 
boll weevil has changed all this. After the careful studies that have 
been given the problem it is evident that no top crop of cotton can 
be expected in infested regions. This, of course, reduces the leaf- 
worm to an insect of no importance where the boll weevil exists. 
The change has actually been even greater than this, for the work 
of the leaf-worm has a disastrous effect upon the boll weevil. As 
has been pointed out in the discussion of fall destruction, the late 
developing weevils are the ones that pass through the winter. Con- 
sequently, if the leaf-worms defoliate the plants and stop the forma- 
tion of squares, a certain degree of fall destruction is accomplished. 
It can never be so satisfactory as the poorest artificial fall destruc- 
tion, because the plants continue to leaf out after the defoliation by 
the worms, thus giving the weevils a supply of succulent food. It is 
not recommended that the work of the leaf-worm be depended on in 
place of fall destruction. Nevertheless, allowing the leaf-worms to 
proceed with their work, or even encouraging them, will assist as a 
general procedure against the boll weevil at least when, for ‘any 
reasons, the more important steps are not taken. In some cases where 
the injury by the leaf-worms begins unusually early, it may still be 
adviszble to check it by poisoning in the well-known manner, but 
512 
