Landscape, Nursery, and Greenhouse - Tarnished Plant Bug

One insect that can cause considerable damage to flowering plants is the tarnished plant bug. It often goes unnoticed until too late. They will feed on leaves but are a bigger concern feeding on buds, flowers, and young fruit. They can also attack conifer seedlings. Numbers have been high this year. The following is some information.

Tarnished Plant Bug


Tarnished Plant Bug. Photo by Russ Ottens, University of Georgia, Bugwood.org

Many times growers see pest damage before they notice the pest. This is usually the case with the tarnished plant bug. Symptoms of feeding can result in injury to flower buds, causing them to abort and drop, or the blooms not to open properly or be distorted on one side. Other types of injury include deformed leaves, scarred and discolored stems, or leaf petioles. The tarnished plant bug is a very general feeder, attacking many kinds of trees and herbaceous plants. It feeds on many flowers including dahlia, aster, calendula, chrysanthemum, cosmos, gladiolus, poppy, salvia, daisy, sunflower, verbena, zinnia, and others. It has piercing-sucking mouth parts as do all the true bugs. The long sucking mouthpart is inserted into the plant tissues and introduces toxic saliva into the plant as it feeds. The toxin kills cells near the feeding site causing the distortion of the growth surrounding their "sting marks", yellow or brown spots or wilting of new growth. The heaviest injury often occurs during mid to late summer and is most evident during hot, dry weather, especially adjacent to recently cut hay fields. The first few generations develop on preferred hosts such as small grains, alfalfa, wild grasses, vetch, dock, and fleabane. As hay is cut or as other plants dry out, tarnished plant bugs migrate in large numbers to succulent hosts, which may be your flowers.

The adult is a small, flattened bug, about 1/4" in long, bronze in color with yellow and black markings. There is a clear yellow triangle, marked with a black dot on the lower third of each side. Tarnished plant bugs have a gradual type of development, and the young become more and more like the adults as they go through each stage. Young tarnished plant bugs, called nymphs are small, green and resemble immature aphids. As they get larger, they look similar to the adults except they have wing pads. Adults will fly when disturbed or they will run rapidly and hide underneath the leaves. There are several generations each year throughout the summer.


Foliar sprays of a label pesticide can be applied when plant bugs appear in the field or landscape, and reapplied as needed. There are differences of opinion as to the best timing for treatment. One source recommended treating early in morning when the bugs are still sluggish from cooler temperatures. Another source, for orchards, recommended treating on a warm, sunny, calm day when TPB are most active. All sources however, strongly recommended weed control to reduce overwintering populations. Read labels to determine whether specific products are registered for use against plant bugs on target flowers. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity.

Some foliar sprays registered for use against plant bugs on ornamentals include:
Acephate (Orthene 97, Orhtene TT&O), Bifenthrin (Talstar Nursery), Carbaryl (Carbaryl 4L, Sevin 80WSP, Sevin SL), Cyfluthrin (Decatholon 20WP), Fluvalinate (Mavrik Aquaflow), Insecticidal soap (I.S. 49.52 CF, M-Pede), Malathion (Malathion 5 EC), Pyrethrins (Pyrenone Crop Spray), Pyrethrins + rotenone (Pyrellin)


Information from a factsheet by Tina M. Smith, Extension Specialist Floriculture Program, Dept. of Plant, Soil & Insect Sciences, University of Massachusetts, Amherst