Tarnished plant bugs in strawberry

The tarnished plant bug, Lygus lineolaris, or TPB can create some serious problems for strawberry growers this time of year, as their damage leads to misshapen fruit. This pest is a True Bug, meaning it feeds using piercing-sucking mouthparts and develops through incomplete metamorphosis; eggs hatch into nymphs that look like adults but increase in size as they grow and wings are present when they reach their adult stage. TPB overwinter in their adult form (Fig. 1) and move into production areas in spring. This insect pest can cause economic damage because of their tendency to feed on buds and developing fruit, resulting in misshapen berries. They feed on all parts of the developing fruit by injecting their mouth parts into the plant tissue. Their long stylet (straw-like appendage) is lubricated with salivary secretions that cause localized cell death as the probe into the plant. The resulting damage is often described as cat-facing or button-berries. To distinguish TPB damage from poor pollination you must closely inspect the achenes on the berry. Poor pollination will result in achenes of various sizes on a single fruit while TPB damaged fruit will have full achenes, but the flesh is often sunken in; berries often have ‘seedy tips’ and indentations with a seedy appearance (Fig. 2)

Monitoring

Be sure that you can recognize both the nymph and adult forms of this pest. Nymphs look like aphids and are bright green in color in their earliest stage (Fig. 3), as they get older, they begin to darken in color and develop brown/black spots where the wings will form. This stage is the most damaging to fruit development as it often overlaps with flowering and fruit set. Adults are flattened, oval to shield shaped and approximately 6 mm (1/4 inch) long. They are black to bronze in color with mottled spots/stripes along their body. Their wings are not obvious as they are held back, folded flat against the body.

Figure 3: A tarnished plant bug nymph feeding on a strawberry flower. Photo by Robert Grosdidier.

The key development times to start monitoring your strawberry crop for TPB is from the white bud stage to early fruit set. Scout 1-2 times per week. There are a variety of scouting plans available from difference Extension sources but the most important thing to note is what and how to find TPB. When sampling, you should use a white paper or pan held underneath the plant. Focus on clusters of buds/blooms and shake vigorously over the white surface. Then count the number of adults and nymphs dislodged. If you have a history of TPB damage you likely want to intervene when they are first detected. If it is not a common pest for you, then you may want to follow recommended thresholds which vary but are around 4.5 nymphs per 30 clusters.

Management Strategies

Cultural

One way to minimize damage inflicted on strawberry plants is to manage broadleaf weeds around your strawberry patch and avoid planting near alfalfa or small grain fields or other vegetative habitats that will be disturbed during strawberry bloom. As little as 300-600 feet of separation can reduce TPB pressure.  Avoid mowing or treating weeds in and around the crop starting 3-4 weeks prior to bloom and throughout the flowering period. Trap crops that have been shown to be effective at drawing TPB away from strawberries include buckwheat, white mustard, small strips of alfalfa, and canola/rapeseed. It is important to note that these trap crops need to be managed, either with chemical applications or physical removal (vacuuming) to restrict TPB population growth and spillover into the cash crop.

Chemical

The Midwest Fruit Pest Management Guide, which was just updated for 2026-2027, has an excellent table of spray recommendations for the prebloom treatment of TPB. A selective conventional insecticide is the active ingredient flonicamid (Beleaf®). It manages piercing-sucking plant pests, is safe for natural enemies, and can be applied as a foliar spray or soil drench. Regardless of what you choose, check the label- it is the law.