136 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
worms can be disturbed and knocked down or brushed off from the 
plants has, to some extent, a beneficial influence in lessening the num- 
ber of the worms, the explanation being that once on the ground they 
can be crushed in some way or that they are very liable to the attacks 
of the ants. In very hot and dry weather the knocked-off worms are 
very often unable to regain the plant, and perish on the hot soil. Thus, 
frequent cultivating and working of the cotton will have some benefi- 
cial effect in this regard, and a number of contrivances have been sug- 
gested to expedite this mechanical method of killing the worms. One 
of the best, in the words of Dr. J. D. Hoyt, of Livingston, Ala.,* "is to 
drag something like a piece of cotton-bagging along over the rows of 
cotton, forward and back, which may be long enough to extend across 
several rows, and having short lines attached to one edge, a little fur- 
ther apart than the width of the rows, and a hand at each line, and all 
abreast pass along between the rows, and then back ; when the brush- 
ing and shaking of the stalks by the bagging will clear the cotton 
mostly of the worms. In this way a set of hands can go over their crop 
in a day or two, when they should return to the beginning and go over 
again, and continue so doing as long as any number of worms are found 
on the stalks." At best, however, only a portion of the worms are 
knocked off, for no amount of shaking or brushing, even when violent 
enough to injure the plants and knock off the bolls, will dislodge all the 
worms, and particularly will not disturb most of the young ones. 
As this subject will, however, be treated of in its proper place in 
Chapter XIII, we will pass at once to the consideration of the sub- 
stances which may be employed against the worm. 
POISONING THE WORMS. 
MINERAL INSECTICIDES. 
With the introduction of mineral poisons for the destruction of the 
worms a new impetus was given to the invention of machines and con- 
trivances for the application of these poisons either as powder or in 
water. The large number of such inventions that have been perfected, 
and the activity still displayed in adding improvements, furnish evi- 
dence that this poisoning of the worms has so far proved most satis- 
factory in protecting the crop. The fact is that a judicious and timely 
application of the best poison will always, even under unfavorable con- 
ditions and in bad " worm years," enable the energetic planter to save 
at least the larger portion of his crop. 
The progress in improving the quality of the insecticides already in 
use, and the discovery of new and more effectual ones, is slower ih:m 
the invention and improvement of machinery, because of the numerous 
difficulties in thoroughly testing any remedy in the field, the most seri- 
ous being the great susceptibility of the cot ton plant to injury by some Of 
* Practical Modes of Destroying tho Cotton Worm ; A Prize Essaj'. Selma, Ala., 1874. 
