~— a 
INSECTS AFFECTING THE COTTON PLANT. 
THE COTTON WORM, OR COTTON CATERPILLAR. 
(Aletia argillacea Hiibn.) 
GENERAL APPEARANCE, HABITS, AND LIFE HISTORY. 
This insect is perfectly familiar to all cotton growers. The slender, 
bluish-green caterpillar with small black spots, and often with black 
_ stripes down its back, which loops when it walks and feeds voraciously 
on both upper and under surfaces of the cotton leaf, is to be found in 
cotton fields in the Gulf States all through the summer. It is gen- 
erally not noticed in the early part of the season on account of its insig- 
nificant numbers. Later, through the ragging of the leaves, it becomes 
noticeable, and in seasons of abundance the plant is entirely defoli 
ated. Farther north the insect makes its appearance at a later date in 
the season, and there the caterpillars are not the offspring of hibernat- 
ing moths, but of the moths of the first or second generation, which 
have developed in more southern cotton fields and have flown north 
with the prevailing southern winds. Late in the season moths of the 
fourth or fifth generation fly far to the north, frequently making their 
appearance in numbers about electric lights in Canada. There is no 
absolute evidence of any other food plant than cotton, although many 
entomologists have surmised that the species has a northern food plant. 
The specimens seen in Canada have, however, in all probability flown 
north from cotton fields in the Carolinas, and perhaps even farther 
south. 
The egg.—The egg is bluish green in color and of a different shade 
from that of the leaf, so that it can be rather readily distinguished. It 
is flattened-convex in shape, with many paraliel longitudinal ridges con- 
verging at the center above. It is found usually on the under side of 
the leaves and as a general thing toward the top of the plant. In the 
neighborhood of 500 eggs are laid by each female, sometimes several 
upon one Jeaf, but never in clusters. The eggs are laid at night, since 
the moth is a night flyer. The duration of the egg state varies some- 
what, according to the season. In midsummer the larva hatches in 
from three to four days after the egg is laid, but in spring and autumn 
this period is very considerably lengthened. 
The larva.—After hatching from the egg, the young larva feeds at 
first upon the under side of the leaf, devouring simply the lower paren- 
chyma and uot piercing through to the upper side until after the first 
3 
