Redshouldered Stink Bug in Soybean
Crop Damage
Redshouldered stink bug (Thyanta custator) occurs throughout the United States and in southern Canada. They are considered a minor pest in many fruit, vegetable, and field crops, including soybean. Both nymphs and adults use their piercing-sucking mouthparts to feed on soybean leaves, stems, flowers, pods, and seeds. As they feed, they inject digestive enzymes that damage plant tissue and expose the area to pathogens. Redshouldered stink bugs cause the greatest economic damage when they feed on developing pods and seeds. They are often confused with redbanded stink bugs, which are a serious pest in soybeans in the southern region of the U.S.
Redshouldered stink bug nymphs.
Herb Pilcher, USDA ARS, Bugwood.org.
Pest Description
Young nymphs are dark brown to black with two distinct white to yellow spots on each side of the abdomen. As they mature, nymphs develop distinctive white and black stripes across the abdomen. Adults are approximately 1/2 inches long and have sharp pointed edges on the shoulders (pronotum). Their coloration varies seasonally, appearing green during the summer and brown in the fall. Adults may have a distinct red stripe across the pronotum, a red tip at the bottom of the triangle on the back (scutellum), and black spots on the exposed wing membrane near the end of the abdomen. The sharp edges of the pronotum and the absence of a long abdominal spine on the underside of the body are key characteristics that distinguish redshouldered stink bugs from redbanded stink bugs.
Redshouldered stink bug nymphs.
Herb Pilcher, USDA ARS, Bugwood.org.
Redshouldered stink bug adult. The white arrow indicates sharp edges of the pronotum. The blue arrow indicates the red tip on the scutellum. The black arrow indicates black spots on the wing membrane.
Whitney Cranshaw, Colorado State University, Bugwood.org
Scouting and Management
Depending on the state, scouting for stink bugs is recommended when soybeans begin blooming (Stage R1) and may continue until full maturity (Stage R8). Most states recommend using a sweep net to monitor stink bug populations. Take 25 sweeps in 4 locations throughout the field. Larger fields may require additional sampling locations to obtain an accurate estimate of stink bug populations. Count the number of older nymphs and adults. Common insecticide treatment thresholds for stink bugs when using a sweep net are 9 stink bugs per 25 sweeps (40 stink bugs per 100 sweeps) for grain production fields and 5 stink bugs per 25 sweeps (20 stink bugs per 100 sweeps) in seed production fields. Timing of scouting and treatment thresholds vary by state, so consult with local or state extension specialists for current scouting and treatment recommendations. If multiple stink bugs species are present, assess their potential impact before making management decisions. If treatment is warranted, consider the pre-harvest interval (PHI) when selecting an insecticide for late-season applications.
Developed and reviewed by Carol Pilcher, Iowa State University and Robert Wright, University of Nebraska-Lincoln, with support from the United Soybean Board.
Redshouldered stink bug nymphs. Herb Pilcher, USDA ARS, Bugwood.org.
Redshouldered stink bug nymphs. Herb Pilcher, USDA ARS, Bugwood.org.
Redshouldered stink bug adult. The white arrow indicates sharp edges of the pronotum. The blue arrow indicates the red tip on the scutellum. The black arrow indicates black spots on the wing membrane. Whitney Cranshaw, Colorado State University, Bugwood.org.
Redshouldered stink bug adult. The white arrow indicates the sharp edges of the pronotum. Whitney Cranshaw, Colorado State University, Bugwood.org.
Gallery images courtesy of Herb Pilcher, USDA ARS, Bugwood.org and Whitney Cranshaw, Colorado State University, Bugwood.org.
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