Tarnished Plant Bug
Contact: Eric Day, Manager, Insect Identification Laboratory
Publication 444-227, August 1996
Adult Tarnished Plant Bug
Plants Attacked
Strawberries, vegetables, tree fruits, and flowers
(dahlias, chrysanthemums, marigolds, zinnia, and many others).
Description of Damage
Adults emerge in the spring and attack swollen overwintering buds on
trees and shrubs. This causes leaf deformities and debudding, which
ultimately can lead to bushiness. Shoots may be distorted or stunted
if the attack occurs after shoot elongation. Later in the growing
season, all life stages will be present and feeding. On flowers,
nymphs and adults puncture the terminal shoots beneath the bud and
inject a poison which usually causes the flower to wilt and die. On
leaf buds, feeding causes spotting and a general bronzing effect on the
leaves. A condition called catfacing can occur on tree fruits and
vegetables when the tarnished plant bug feeds on the developing fruit.
Damage when the fruit is small can cause the fruit to be deformed and
misshapen when it reaches maturity, thus catfaced. The fruit may also
be aborted and drop to the ground if it is too heavily damaged. The
feeding damage on strawberries is called "buttoning".
Identification
The adult is a small insect, about 1/4" in length. It is light brown
and variously spotted. The white, yellow, and black spots give the
insect a tarnished appearance, but there is a clear yellow triangle,
marked with a black dot on the lower third of each side. The young
tarnished plant bugs, called nymphs are similar to the adults except
they have wing pads. The tarnished plant bug, Lygus Lineolaris
(Palisot de Beauvois), is in the order Hemiptera, family Miridae.
Life History
The adults and older nymphs hibernate under leaf litter and rocks.
These individuals become active during the first warm days of spring.
They feed on early buds of their host plant, but breed in grasses.
Eggs are generally laid on the midrib of leaves and sometimes are
inserted into the plant buds. Ten days later, the eggs hatch. The
nymphs usually remain on the plant upon which they hatch, but may move
to adjacent plants. The adults have wings and readily move from weeds
to fruit trees.
Control
Some varieties may be resistant to attacks by tarnished plant bug,
particularly fruits with many plant hairs. Check the Virginia Pest
management Guide for current chemical control recommendations for the
tarnished plant but and other bugs. Insecticide treatments probably
are only partially effective. Plant bugs are active and move about
freely, thus avoiding the treatment. Feeding injury can resume as soon
as the effectiveness of sprays dissipates.
Remarks
Minor plant bug injury is tolerable, although unsightly. Controls are
necessary for severe infestations.