Insect Management
Cotton Insect Management
Cotton Aphid -
Aphis gossypii (Glover)
Description
The aphid is a soft bodied insect with all stages ranging in color from
light yellow to dark green or almost black. The aphid is a very slow moving
insect that secretes honeydew causing the leaves to be sticky or shiny.
Biology
The aphid reproduces very rapidly during favorable conditions. Large
populations build up in a short period of time. Females give birth to living
young; reproduction is continuous; and there are no distinct generations. A new
generation can occur every five days during the summer. The cotton aphid has
many natural enemies such as syrphid fly larvae, parasites, and others. Natural
enemies and weather conditions help control aphids during the growing season.
Damage
Aphids damage cotton by sucking juices from the plant and by secreting
honeydew. High populations in young cotton cause the leaves to curl or crinkle.
This causes young plants to become stunted and die. Aphid damage causes leaves
to cup downward. When infestation occurs during the main fruiting period, the
older leaves may turn yellow and shed. Squares and bolls drop off as a result of
severe leaf shed. During late season, honeydew secretion falls on open cotton
causing a black sooty mold to develop. In severe cases, the mold stains the lint
or causes sticky lint. This is a serious problem for cotton mills.
Scouting
To determine infestation levels, observe aphid populations while walking
cotton fields. Classify the population depending on the number present.
None - No aphids present.
Light - Aphids on an occasional plant, 1 to 10 per leaf.
Medium - Aphids on numerous plants and some leaves curling
on edges, 11-25 per leaf.
Heavy - Aphids on numerous plants and leaves are crinkling and
curling. More than
26 per leaf are present. A deposit of honeydew is readily visible and the
leaves and
plants feel sticky.
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