Insect Management
Cotton Insect Management
Plant Bugs
Three species of plant bugs attack cotton. They are the
cotton fleahopper, clouded plant
bug, and tarnished plant bug.
Cotton Fleahopper - Pseudatomoscelis
seriatus (Reuter)
 Description
The cotton fleahopper egg is glistening white in color and found embedded in
stem tissue. The egg shape is slightly curved, enlarged at one end and has a
truncate flat cap at the other end. The small nymph (or immature) is white and
translucent at first then becomes a pale green after feeding. Nymphs range in
size from very small up to about 1/8 of an inch long. The nymphs have prominent
scarlet colored eyes and resemble adults but have no wings. The adult is about
1/7 of an inch long. The pale green body is dotted with tiny dark spots.
Biology
The cotton fleahopper hibernates (or overwinters) in the egg stage. Eggs of
the cotton fleahopper hatch in 6 to 12 days and complete development to adult
requires 16 to 29 days. Croton is the preferred food plant of this insect.
However, it feeds on a large number of other host plants including cotton,
horsemint, wild sunflower, and horsenettle.
Damage
Tiny, active, hard-to-see nymphs and adults feed on juices of tender plant
parts -especially the terminal buds and small squares. Deformed or ragged leaves
are often seen as a result of this feeding. The greatest damage is to small
squares that are no larger than a pinhead. They turn brown or black and shed
after being fed upon. Heavily infested plants grow tall and whip-like, have
restricted growth of fruiting branches, and usually produce only a few bolls
near the top.
Scouting
The shake sheet and small square set are the methods used in scouting for
plant bugs. The diagnostic key in the color picture section will aid in
determining the cause of small square shed. Fields should be scouted for plant
bugs until about 2 weeks past peak squaring and when the majority of bolls are
set.
Clouded Plant Bug - Neurocolpus
leucopterus (Say)
Description
The clouded plant bug adult is a tan color and slightly larger than 1/4 inch
in length. The first segment of the antennae next to the body is quite large and
the first segment of the hind legs is strikingly larger than the front legs. The
antennae has prominent black and white alternating bands.
A very young nymph of the clouded plant bug resembles a tiny spider with a
small hairy body and long legs. The top of the body is covered with small black
hairs and there are red bands on the legs and antennae. The eyes are large and
bright red. Larger nymphs are pear shaped, green in color, and have prominent
alternating black and white bands on the antennae and hind legs.
Biology
The clouded plant bug has three stages of growth - egg, nymph, and adult.
Clouded plant bugs feed on evening primrose, goldenrod, honeysuckle,
johnsongrass, morningglory, smart weed, stink weed, cotton, soybean, alfalfa,
button bush, black willow, and others. Adult females lay several eggs that hatch
in 12-14 days. Eggs are deposited singly by the female in slits made in the
plant tissue. The nymph requires about 12-15 days to reach the adult stage. The
clouded plant bug overwinters in the egg stage. Three to four generations occur
per year.
Damage
Clouded plant bug adults and nymphs feed by inserting their mouth parts into
small squares, flowers, bolls, and tender plant tissue. The feeding causes
discolored anthers in squares and blooms. Small bolls shed as a result of
feeding. Small spots occur on bolls marking the feeding points. The spots are
dull black with a pinhead sized, glossy black spot near the center of the larger
dull spot. The lint inside the boll may be stained a tan color around the entry
point. Malformed bolls may result with damage being done to the entire boll or
in tiny spots. Occasional malformation results from improper development of one
or more boll locks following heavy anther feeding but no discoloration is
usually seen. The symptoms of feeding on vegetative parts are wilted or
blackened leaves, lesions, knotted or swollen areas on stems and petioles,
malformed or tattered leaves, and excessive branching of the main stem at some
nodes.
Scouting
The shake sheet and small square set methods are used in scouting for plant
bugs. The small square shed diagnostic key in the color picture section will aid
in determining the cause of small square shed. Fields should be scouted for
plant bugs until about 2 weeks past peak squaring and when the majority of bolls
are set.
Tarnished Plant Bug - Lygus
lineolaris (Pialisot de Benuvois)
Description
The tarnished plant bug has three stages of growth - egg, nymph, and adult.
The adult has a brown colored body mottled with small irregular patches of
white. On the rear third of the body, along the side, is a clear yellow triangle
tipped with a small, triangular spot. The nymph is light green with long
antennae and has five black dots on its back. Four of these black dots take the
shape of the corners of a square. The nymph has no wings. The nymph moves
quickly and resembles the adult as it approaches maturity. The tiny elongated
and slightly curved eggs are laid by the adult in small slits made in the cotton
stem.
Biology
The tarnished plant bug feeds on many alternate hosts such as alfalfa and
other legumes, butterweed, fleabane, goldenrod, aster, and dog fennel. When the
weed host becomes unsatisfactory for feeding purposes, plant bugs usually
migrate to cotton or other host plants growing nearby. The average time to
complete the life cycle is 30 days in summer. Four to seven generations occur
per season.
Damage
Tarnished plant bugs feed by inserting their long needle-like mouthparts into
tender terminals, squares, and other tissues, and by sucking the juices out.
Injured squares usually turn dark and drop off, while damaged bolls may develop
abnormally. Terminals fed on may branch out abnormally.
Scouting
The shake sheet and small square set are the methods used in scouting for
plant bugs. The diagnostic key in the color picture section will aid in
determining the cause of small square shed. Fields should be scouted for plant
bugs until about 2 weeks past peak squaring and when the majority of bolls are
set.
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