Tarnished Plant Bug

The adult bug is a small, flattened light brown insect, about ¼ inch long. It is mottled with splotches of white, yellow, reddish-brown, and black, giving the insect a tarnished appearance. There is a clear yellow triangle, marked with a black dot on the lower third of each side. The wings have a hard wing cover similar to that of a beetle with a smoky-brown membranous tip. The greenish-yellow nymphs are very small and are marked dorsally with four black dots on the thorax and one dot on the abdomen.

The tarnished plant bug is a common pest on numerous vegetable, fruit and flower crops, as well as a number of weeds. Vegetable hosts include bean, beet, cauliflower, cabbage, chard, celery, cucumber, potato, turnip, and dill; fruits include apple, peach, pear, strawberry, and most other deciduous and small fruits. It also attacks many flowers including dahlia, aster, calendula, chrysanthemum, cosmos, gladiolus, poppy, salvia, daisy, sunflower, verbena, zinnia, and others.

Damage

Adults emerge in the spring and attack swollen overwintering buds on trees and shrubs. This causes leaf deformities and debudding. Shoots may be distorted or stunted if the attack occurs after shoot elongation. 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 of small fruit 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".

Life Cycle

The adults and older nymphs hibernate under leaf litter, bark, and rocks through the winter. They emerge early in spring and fly to host plants where they feed on early buds of their host plant, later migrating to other plants to lay eggs on the leaves or flowers; eggs hatch ten days later. The nymphs usually remain on the plant upon which they hatch, but may move to adjacent plants. The life cycle is completed in approximately three to four weeks and there are from three to five generations per season. By midsummer there may be great numbers of tarnished plant bugs present but they are well camouflaged and often go unnoticed.

Control

Tarnished plant bugs can be difficult to control. Some plant varieties may be resistant to attacks by  tarnished plant bug, particularly fruits with many plant hairs. Insecticide treatments probably are only partially effective. Plant bugs are active and move about freely, thus avoiding treatment. Feeding injury can resume as soon as the effectiveness of sprays dissipates. Cultural control practices include the removal of weeds and the elimination of trash and other debris which could provide overwintering sites. Mowing grass and weeds around gardens may also help to reduce breeding sites. Verify that insecticides are labeled for use on the tarnished plant bug and follow label directions carefully.

Adapted from G.R. Nielsen, University of Vermont Extension, 1999; Virginia Tech Cooperative Extension