Common Name: Tarnished plant bug
Scientific Name: Lygus lineolaris Palisot de Beauvois
Description:Adults are oval, flattened insects about 1/4 inch long, predominantly copper-brown with some whitish-yellow markings, particularly near the end of each front wing margin just before wings turn clear and black tinted. Nymphs are similar to adults but lack wings and are greenish and marked with black spots on the segments (prothorax, metathorax) behind the head.
The lygus bug, Lygus hesperus Knight, is a similar species, causing injury to alfalfa, cotton, beans, carrots and other herbaceous plants. When nymphs first hatch they are green with an orange spot in the middle of the abdomen. Adults are marked similar to tarnished plant bug but have a light-colored triangle (scutellum) in the middle of the body between the base of the front wings. This and other species are commonly called “lygus bugs” while members of this family (Miridae) are also called “plant bugs.”
Life Cycle: Adults overwinter in protected habitats and become active in the spring. Females lay whitish elongated eggs into or on host plants that hatch in about 8 days. Tiny nymphs (1/25 inch long) are pale green when they first hatch. They feed and develop through five stages (instars) as they grow, change color and develop wing pads before becoming adults. Development from egg to adult takes about 3 to 4 weeks, and three to five generations can be produced each year.
Habitat, Food Source(s), Damage: Tarnished plant bugs feed on a wide variety of plants, including alfalfa, beans, beets, cabbage, cauliflower, chard, celery, cotton, cucumber, pecans, potatoes, salsify, turnip, many flowering plants, small fruit and nut trees, grasses and weeds. Plant bugs inject a toxic saliva into the plant during feeding.
On fully developed leaves, injury appears as yellowish (chlorotic) spotting while on leaves injured in the bud stage or during leaf expansion appear distorted. Feeding on cotton squares (buds) or small bolls (fruit) usually causes them to fall off the plant. Injury to buds of developing fruit causes them to become dwarfed and pitted (a type of injury called “cat-facing”). Injury to young peach trees can result in twigs and terminal branches wilting and dying, later causing trees to appear bushy or scrubby.
Pest Status: Can injure a wide variety of plants; medically harmless.
Management: See Insects in Vegetables.
Literature: Bohmfalk et al. 1982; Metcalf et al. 1962; Slater and Baranowski 1978.