COTTON LEAFWORM 
(Alabama argillacea (Hbn.)) 
Injury and Life History 
The cotton leafworm is a tropical insect not known to survive the 
winters in the United States. New infestations are started each spring 
by moths that fly in from the South and lay their eggs on cotton. The 
first leaf worms generally appear in April, May, or June, usually in 
southern Texas but sometimes in Florida. As the leaf worms increase 
in numbers, the moths fly to other areas, and in some years all the cotton 
States except California are invaded. The moths often reach the 
Northern States and Canada and feed on ripe fruit, such as peaches or 
grapes. The larvae, or “worms,” feed only on cotton. The small leaf- 
worms feed on the under side of the leaves and do not cut through the 
upper surface. The larger worms eat the entire leaf and when abundant 
completely strip, or “rag,” the leaves and then gnaw on the squares, bolls, 
and bark until the field looks as if it had been swept by fire. The brown 
pupae are formed within a folded leaf or are attached by a silken cord 
to the stems and ribs of the leaves. 
The spread of the leafworm varies greatly from year to year. 
Although damage is usually greater west of the Mississippi River, 
control is often needed in the Eastern States. Early ragging of the 
plants prevents bolls from maturing and causes reductions in the yield 
and quality of the cotton. The stripping of the leaves by leafworms 
after most of the bolls are mature may be beneficial in preventing boll 
weevils from increasing and in keeping the bolls from rotting on rank 
cotton by admitting more sunlight to the plants and permitting better 
circulation of air. 
Control 
Small cotton leafworms can be controlled very easily by dusting or 
spraying with any of the arsenical insecticides. Large worms are more 
difficult to control and may cause considerable stripping before they are 
killed. Dusting with 5 to 7 pounds per acre of calcium arsenate or lead 
arsenate will control leafworms. Lead arsenate applied as a spray at 
the rate of 4 to 6 pounds in 50 gallons of water for each 3 acres is also 
satisfactory. If a quick kill of large worms is needed to prevent 
stripping, add 7 or 8 pounds of paris green to each 100 pounds of 
calcium arsenate, or use 8 to 10 pounds of paris green with 100 pounds 
of lime. 
April 1946 U. S. Government Printing Office 
For sale by the Superintendent of Documents, Washington 25, D. C. Price 5 cents 
684388 — 46 
