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Copyright 2005, Board of Trustees, University
PRESS BULLETIN 194
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
THE COTTON CATERPILLAR
BY J. R. WATSON
Because this insect was rather destructive to cotton during August and
September of 1911, a close watch has been kept for its appearance this year.
It has often happened that during a series of years this pest almost com-
pletely destroys the cotton fields. This time of abundance is then followed
by a series of years during which it is almost or totally absent.
This year, 1912, is apparently to be a caterpillar year, the insects having
been found in Suwannee County by the Experiment Station Entomologist.
While they are not yet in destructive numbers, enough are present to make
it probable that they. will be a serious menace to the cotton crop before the
end of the season.
The arsenical poisons have proven quite effective and satisfactory.
These can be most economically applied as a dry powder. Make two bags
of some porous cloth (eight-ounce Osnaburg is good). These bags should be
large enough to hold about a quart of poison. Fill them with the poison,
and so fasten them to a pole that the distance between them is equal to the
distance between two rows. Let a man or boy mount a mule and ride down
every other row, jarring the pole as he rides. By this method he can dust 18
or 20 acres a day. This is best done, however, when the plants are wet with
dew or rain. At this time of the year powdered lead arsenate is the best to
use, unless the newer insecticide, zinc arsenite, can be obtained. Paris green is
cheaper, but it has been found that it seriously checks the setting of bolls.
Use as many pounds per acre of the lead arsenate as the cotton is feet in
It is urged that a supply of lead arsenate or zinc arsenite be obtained at
once and be prepared for the pest. Since the cotton caterpillar has also
July 2 7, 1912
appeared in other States, there will be an immense demand for the insecticide,
and quite possibly the supply may be exhausted. A week's delay in securing
the poison is sufficient to ruin the crop.
Except possibly in the most southern part, this insect does not live over
winter in the United States. It migrates each year from regions farther
south. The moth is a long-distance and powerful flyer, having frequently
been taken in Canada. As the insect, as far as known, feeds only on cotton,
the moths must have flown to Canada from at least the cotton fields of Ten-
nessee and Virginia. This explains their ability to migrate over the cotton
belt in two or three generations. The insects taken in Suwannee County
had webbed up, and entered the pupa stage. In from one to four weeks the
moths will issue from these pupae. They measure about one and one-fourth
inches across the wings, and are brownish or clay-colored. They hide in the
cotton foliage during the day and fly about towards night. Each female lays
about five hundred eggs. These she places singly about on the leaves. In
three or four days they hatch out into caterpillars which feed greedily on
cotton leaves. They become full grown in two or three weeks. They then
roll up a leaf by means of a few threads of silk and turn into a brown pupa
one-half inch long. In the summer, each brood or generation requires only
about a month for its development. There is still time for at least three
more broods this season in Florida. By October, if none were destroyed,
each insect now on the cotton would have over thirty million descendants.
The August brood will probably be sufficiently numerous to do serious
damage in some counties. The September brood may be expected to strip
many fields completely unless prompt measures are taken to poison the
caterpillars. As the cotton is late this year, more damage may be done than
State papers please copy.