Bug, Nysius raphanus
False chinch bug adults are about 3-4 mm or 1/8 – 1/6 inches long and grayish brown with slender bodies and long antennae. The wings form a distinct x-shaped mark on the back.
Nymphs are smaller than adults and lack wings, although they do have wing pads that enlarge as the nymphs feed and grow. Nymphs are usually gray with a red or orange mark on the back.
- False chinch bugs often occur in aggregations, sometimes thousands of individuals are found on single plant. Usually, these insects aggregate on plants that are flowering or producing seed.
- False chinch bugs favor plants in the mustard family such as radish, canola, and mustard greens. However, they can also feed on plants unrelated to mustard such as potato, lettuce, quinoa, pigweed, kochia, and turfgrass.
- False chinch bugs are not common in Colorado. However there have been infestations reported in Denver area lawns and more frequently in lawns in Tri-River counties of the West Slope.
University of California, Bugwood.org
False chinch bugs are insects with piercing-sucking mouthparts. Adult chinch bugs occasionally aggregate in the thousands on a single plant; however, they do not usually cause serious injury to plants that receive sufficient irrigation.
False chinch bugs aggregating on hemp. Leaf necrosis in the foreground may be caused by the large number of false chinch bugs feeding on the plant. Damage to hemp is minimal.
False chinch bug nymphs and adults. Note that nymphs are either wingless or have incompletely formed wings.
Feeding injury on pine caused by false chinch bug.
Damage caused by high populations of false chinch bug.
Life History and Habits
False chinch bugs undergo incomplete metamorphosis and have three life stages: egg, nymph, adult. This insect produces multiple generations per growing season and occasionally causes injury to certain plants in the mustard family. False chinch bugs also overwinter on plants of the mustard family, most notably flixweed, which is a common weed in alfalfa fields and field margins in eastern Colorado. When temperatures rise in the late winter or early spring, eggs are laid in soil near the base of a host plant.
Upon hatching, nymphs are wingless and smaller than adults. As the nymphs feed and grow, their wing pads increase in size and become more noticeable. These insects feed on plant fluids, and adults will migrate to areas with higher humidity as needed. At times, adults may be encouraged to migrate to buildings adjacent to irrigated landscapes. They can aggregate in the thousands, sometimes on a single plant, which puts drought stressed plants at risk of feeding injury.
Feeding by false chinch bugs does not usually cause significant injury. However, leaf wilting and dieback can occur when false chinch bugs aggregate, especially on drought stressed plants. Aggregations are typically confined to a small area of the field and can suddenly disappear when adults disperse to find new sites.
Control of false chinch bugs is rarely warranted, especially if plants are sufficiently watered. However, row covers or caps can help protect seedlings if they are grown near uncultivated areas containing mustard. This helps protect younger plants when false chinch bugs migrate, which usually lasts about one week.
Insecticides provide minimal control as false chinch bugs tend to recover within a few hours after the knock-down effect immediately following the insecticide application. For more information on false chinch bug management, consult the full factsheet here
Haviland, D. R. & W. J. Bentley. 2010. False Chinch Bug. Uinversity of California: Agriculture & Natural Resources. Available http://ipm.ucanr.edu/PMG/PESTNOTES/pn74153.html
Utah State University. (n.d.). False Chinch Bug. Utah State University: Extension. Available https://extension.usu.edu/pests/schoolipm/structural-pest-id-guide/false-chinch-bug