COTTON APHID 
( Aphis gossypii Glov.) 
Life History 
The cotton aphid, also known as the cotton louse and the melon aphid, is found 
throughout the United States. It is a general feeder and, in addition to damaging 
cotton, is a pest of okra, melons, squash, cucumbers, and other cucurbits. It is a 
small, soft-bodied, sucking insect, its color ranging from light yellow to dark 
green or almost black. In the Northern States both sexes occur and eggs are laid, 
but in the South only females that give birth to living young are known. Some 
of the adults are winged for flying to other plants, while others are wingless. The 
aphids spend the winter on various weeds, from which they spread to cotton early 
in the spring. Reproduction is continuous throughout the year in the South and 
becomes very rapid during warm weather. There are no distinct broods, and 
aphids of all sizes are present on the under side of the leaves and on the stems 
of plants. The natural controls, such as ladybird beetles and other predators, 
parasites, diseases, and unfavorable weather, are important factors in controlling 
aphids. Aphids are present in almost every field of growing cotton, and during 
cool, wet springs they often cause curling of the leaves, stunting of growth, or 
even the death of small cotton seedlings. The greatest damage, however, is done 
later in the season by causing the leaves to curl and fall from the plant before 
the bolls are mature. The premature shedding of leaves causes serious losses in 
yield and grade of cotton. Aphids secrete a sticky substance known as honeydew, 
which drops on the leaves and bolls below and gives the plants a glossy ap- 
pearance. A fungus often develops in the honeydew and causes the plants to 
appear black, or sooty. Honeydew falling on the open bolls also makes the lint 
gummy and difficult to gin. 
Control 
Aphids are more likely to damage cotton that has been dusted with arsenicals or 
DDT than they are undusted cotton. It is more profitable to prevent the aphids 
from becoming numerous by adding nicotine to the calcium arsenate or other dusts 
used to control cotton insects than it is to control an aphid outbreak. Adding 1 
percent of nicotine to the calcium arsenate used in each application, or adding 2 
percent of nicotine to the calcium arsenate used for every other application, will 
prevent aphids from building up injurious populations. After heavy infestations 
have developed, 3 percent of nicotine in hydrated-lime dust at 6 to 8 pounds per 
acre may be needed for control. A 1-percent nicotine dust can be prepared by 
adding 1 quart of nicotine sulfate solution (40-percent nicotine), and the 2- and 
3-percent dusts by adding 2 and 3 quarts of nicotine sulfate, to approximately 
100 pounds of calcium arsenate. Other forms of nicotine, such as free or fixed 
nicotine, are as satisfactory as the sulfate when used at the same strengths. 
Nicotine can be added to DDT dust in the same way as to calcium arsenate. The 
nicotine must be thoroughly mixed with the other insecticides, preferably with 
special mixing machinery in a commercial plant. The best aphid control is ob- 
tained by applying nicotine when the air is very quiet. It is necessary that the 
dust containing nicotine stay down among the plants, not rise and float away as 
often happens when dust applications are made during midday. Complete coverage 
of the plants is necessary. 
April 1946 U. S. Government Printing Office 
For sale by the Superintendent of Documents, Washington 25, D. C. Price 5 cents 
684386—46 
