Tarnished Plant Bug in Soybean
Crop Damage
The tarnished plant bug (Lygus lineolaris) occurs throughout the United States, southern Canada, and northern Mexico. It has a broad host range of over 300 plant species, including soybean. Both nymphs and adults feed using piercing-sucking mouthparts, extracting plant sap and injecting toxic saliva that causes localized cell death. Feeding results in yellow-brown lesions on leaves, flower abortion, and reduced pod and seed development.
A similar species, the western tarnished plant bug (L. hesperus), may be confused with L. lineolaris. This species occurs along the Pacific coast and west of the Rocky Mountains and is a pest of cotton, alfalfa, potatoes, strawberries, and other fruit crops. The western tarnished plant bug is not considered a soybean pest. Both species may occur in Wyoming, Colorado, New Mexico, and Utah, making accurate identification important.
Pest Description
Late-instar nymphs are approximately 1/8 inch long, green, and possess wing pads. They typically have four black spots on the thorax and one on the abdomen. Adults are about 1/4 inch long, flat, oval-shaped, and brown. A distinguishing feature is a yellow triangular marking behind the head, along with forewings that slope downward.
Tarnished plant bug. Orange arrow indicates distinct triangle behind the head.
Russ Ottens, University of Georgia, Bugwood.org
Scouting and Management
Established sampling protocols and economic thresholds for tarnished plant bug in soybean are limited. This pest is commonly associated with alfalfa and weedy hosts, including pigweed, mustards, goldenrod, and lambsquarters. Scouting should focus on field edges, particularly in areas with high weed pressure or adjacent to recently cut alfalfa fields. Weed management along field margins may help reduce infestations. Spot insecticide treatments may be warranted if populations are detected at field edges. Soybeans are most susceptible during pod development stages; therefore, planting earlier-maturing varieties may help reduce the risk of late-season injury. For current management recommendations, consult your local extension specialist.
Developed and reviewed by Carol Pilcher, Iowa State University and Robert Wright, University of Nebraska-Lincoln, with support from the United Soybean Board.
Tarnished plant bug. Orange arrow indicates distinct triangle behind the head. Russ Ottens, University of Georgia, Bugwood.org.
Tarnished plant bug damage. Winston Beck, Iowa State University, Bugwood.org.
Tarnished plant bug nymph. Scott Bauer, USDA. ARS, Bugwood.org.
Gallery images courtesy of Russ Ottens, University of Georgia, Bugwood.org; Winston Beck, Iowa State University, Bugwood.org; Scott Bauer, USDA ARS, Bugwood.org.
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