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BE ON THE LOOKOUT Tarnished plant bugs break down plant tissues with saliva.

Scott Bauer

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Tarnished plant bugs

Garden pests are a blight to plants

By KATE RUSSELL

Tarnished plant bugs feed on more than half of our garden crops, using their piercing mouthparts to suck the life from beans, stone fruits, strawberries and other edibles. While these pests were once only found east of the Rocky Mountains, they now occur throughout North America.

Tarnished plant bugs (Lygus lineolaris) eat all aboveground parts of a plant. They feed by injecting saliva into host plants. This saliva breaks down the pectin and plant tissues, making it possible to suck up their meal. As they feed, they cause distorted and discolored fruit and pod lesions. You may also see growing tips that are distorted, have lesions, or are dying. Affected flowers tend to be distorted, discolored, or have signs of blight. Seeds may be distorted or shriveled. And the entire plant may show signs of dwarfing or rosetting due to tarnished plant bugs. These pests are also responsible for blossom drop of tomatoes and peppers.

Tarnished plant bugs are nearly identical to their western siblings, the Lygus bugs. Like their other relations, the capsid bugs and fourlined plant bugs, this group of garden pests all have a distinctive triangular or V-shape just behind the head and pronotum. This triangular area is called the scutellum. Their wing tips often form a diamond-shaped area at the rear end. Tarnished plant bugs are small, usually 1/4-inch long. They are brown with yellow, orange, or red markings.

Tarnished plant bugs overwinter as adults in weeds and fruit trees. As temperatures begin to rise, females find mates. They prefer laying their eggs in cotton plants, but they will make do with what’s available. These eggs are laid in mid-spring and hatch by early summer. Populations tend to peak when eggs hatch and again in mid-autumn, so be on the lookout.

These pests like to hide in nearby weeds, so keep weeds away from susceptible plants. Mulching those areas with free wood chips from your local arborist will reduce hiding places for pests as well as protect your soil and reduce your water bill.

Tarnished plant bugs have several natural enemies. One nursery web spider, Pisaurina mira, loves to feed on tarnished plant bugs. Some parasitic wasps also play a role in controlling tarnished plant bug populations, so you’ll want to avoid using broad-spectrum pesticides.

While pesticides are commonly used against juvenile tarnished plant bugs in commercially grown crops, the effectiveness of those chemicals is decreasing. And pesticides generally don’t work well on adult tarnished plant bugs. Research has shown that these pests are attracted to pink sticky paper, so that’s an easy organic control method. A strong spray from the hose can dislodge juveniles, who are often unable to find their way back to a host plant.

Be on the lookout for these pests the next time you’re weeding around your fruit trees or garden plants.

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