LESSER CORNSTALK BORER
Lesser cornstalk borer is an important pest in the southeastern
and southwestern growing areas. It is usually a problem during hot,
dry weather, and is more often a problem on coarse, sandy soils
than on heavier soils. Lesser cornstalk borer larvae will feed on
underground pegs and pods in addition to any part of the plant above
ground that contacts the soil surface.
Fall armyworms are one of several foliage feeders that may attack
peanuts. In some years, they can be the predominant foliage feeder.
Caterpillars, gray, light brown or mottled green in color, reach
approximately 1 1/2 inches in length when fully grown and have a
prominant inverted “Y” on their head. When abundant,
fall armyworms can strip plants of foliage and “march”
to other host plants. Female moths lay egg masses of about 150 each
and cover them with scales from their body.
||SOUTHERN CORN ROOTWORM
Southern corn rootworms are most often found on heavy soils that
are poorly drained. During extremely wet weather, they may become
a problem even on sandy soils. This pest is a subterranean feeder.
It may feed on the roots of peanut plants to some extent, but its
most important damage is due to peg and pod feeding. Usually the
holes cut into pegs and pods will be almost a tiny drill bit. In
contrast to lesser cornstalk borer feeding, there is no webbing
associated with this pest.
In peanuts, these two closely related insects are usually referred
to as corn earworms, but tobacco budworms are often a significant
percentage of the total population. Larvae of both species feed
on peanut foliage and are very similar in appearance. The corn
earworm moth (above) and the tobacco budworm moth are often seen
in peanut fields and may indicate that larvae will soon follow.
Leafhoppers are small wedge-shaped, green, brown or black insects
about 1/8 to 1/4 inch in length. Leafhoppers insert their beak into
the midrib on the lower side of peanut leaves and suck plant juices.
Leaves turn yellow from the point where the feeding has occured
to the tip of the leaf and may die in severe cases. This damage
is often referred to as “hopper burn.”
Thrips are tiny, slender insects about 1/32 inch in length. They
vary in color from yellow to black. Adults will have wings and
may fly when disturbed. Thrips feeding often results in stunted
peanut plants with leaves that are scarred and “possum-eared”
(leaf edges are turned down). Thrips also transmit the virus that
causes tomato spotted wilt in peanuts.
Threecornered alfalfa hoppers are light green and wedge-shaped.
They stand about 1/4 inch high and are about 1/4 inch long. Both
adults and nymphs have piercing mouthparts and feed by penetrating
the stem and sucking plant juices. They tend to feed in a circular
fashion around a stem, making feeding punctures as they go (see
photo). The damaged area typically swells and above ground root
growth may occur. On peanuts, feeding may occur on limbs, leaf petioles
Spider mites are not really insects, but are closely related to
insects. Although spider mites are small, they can be seen with
the naked eye, especially if they are moving. Spider mites feed
on peanuts by sucking plant juices from the undersides of the leaves.
This feeding, which usually begins near the midribs of the leaves,
results in a speckling of the upper surfaces of the leaves. As infestations
become more severe, leaves turn yellow and die. Heavy infestations
are characterized by visible webbing.
Wireworms are the immature stages of “click” beetles.
There are many species that damage peanut plants by feeding on the
underground parts. The “worm” stage is always found
in the soil, but finding them may be difficult. Wireworms may be
noticed during land preparation, but usually infestations are often
first noticed as the result of damage to pods. Depending on size,
wireworm damage can vary from small clean holes to large irregular
Insect pests are vulnerable to a vast array of natural enemies.
Control of insect pests by biological agents is the first line
of defense in a sound insect control strategy. Physically moving
beneficial organisms into a peanut field is not practical. However,
avoidance of practices that unnecessarily reduce beneficials will
allow them to work to their maximum potential.
This insect is one of several caterpillars that often feed on peanut
foliage in the southern peanut-producing regions. Although easily
controlled with insecticides, this insect is a voracious feeder
and can do a great deal of damage in only a few days if not controlled.
Damaging populations are most commonly seen late in the growing