False chinch
bug, Nysius raphanus
Order: Hemiptera
Family: Lygaeidae
Description
False chinch bug adults are about 3-4 mm (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 and a red brown to gray abdomen. The eggs are roughly 1.5 mm (~1/20 inch) long and translucent pink or white.
Quick Facts
- The false chinch bug is native to the United States.
- 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. This species is considered an important pest of canola grown in Colorado and other agricultural systems in the arid southwest and Rocky Mountain regions. Infestations have also been reported in Denver area lawns and more frequently in lawns in Tri-River counties of the West Slope.
- This species tends to occur in aggregations, sometimes thousands of individuals are found on a single plant. Usually, these insects aggregate on plants that are flowering or producing seed.
- Control measures include deploying physical barriers such as row covers and the application of certain insecticides.
The false chinch bug is an insect 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. Image credit: University of California, Bugwood.org
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. Image credit: Whitney Cranshaw, Colorado State University, Bugwood.org
False chinch bug nymphs and adults. Note that nymphs are either wingless or have incompletely formed wings. Image credit: Whitney Cranshaw, Colorado State University, Bugwood.org
Feeding injury on pine caused by false chinch bug. Image credit: Chuck Bargeron, University of Georgia, Bugwood.org
Injury caused by high populations of false chinch bug. Image credit: Whitney Cranshaw, Colorado State University, Bugwood.org
Life history and habits
False chinch bugs undergo incomplete metamorphosis and have three life stages: egg, nymph, adult. False chinch bugs overwinter under plant debris or on plants of the mustard family, most notably flixweed, which is a common weed in alfalfa fields and field margins in eastern Colorado. Activity resumes as temperatures rise in the late winter or early spring. Eggs are laid directly on a host plant or in loose soil near the base of a host plant. Upon hatching, nymphs are wingless and smaller than adults. They develop through five instars and their wing pads increase in size and become more noticeable as they feed and grow. 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. The false chinch bug produces multiple generations each year and has been reported infesting many plant species, especially those belonging to the family Brassicaceae. Significant yield losses have been reported in grapes (Vitis vinifera), tomatoes (Solanum lycopersicum), canola (Brassica spp.), cotton (Gossypium hirsutum), and quinoa (Chenopodium quinoa). In addition, research conducted in the San Joaquin Valley of California suggests that outbreaks of the false chinch bug can reduce the abundance of young rangeland shrubs.
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. On canola, this pest can cause severe feeding injuries during flowering and seed-pod development. This can be especially problematic for plant breeders, who often cover canola heads with bags to prevent pollination. However, false chinch bugs can still feed on plants through the mesh.
Cultural control
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.
Chemical control
False chinch bugs tend to recover within a few hours after the knock-down effect immediately following the insecticide application. Although insecticides provide minimal control in some instances, pre- and post-treatment of pollination bags with pesticides can suppress false chinch bug activity. In addition, recent research suggests that foliar spray applications of d-limonene and mineral oil can help reduce populations of this pest.
CSU Extension Fact Sheet
Download or view the CSU Extension’s PDF fact sheet for your reference.
References
Aalaoui, M., and M. Sbaghi. 2022. Field and Laboratory Evaluation of d-Limonene, Mineral Oil, and Potassium Salts of Fatty Acid against Nysius raphanus (Hemiptera: Lygaeidae). Journal of Agricultural and Urban Entomology. 38(1): 1-15. Available https://bioone.org/journals/journal-of-agricultural-and-urban-entomology/volume-38/issue-1/JAUE21-04/Field-and-Laboratory-Evaluation-of-d-Limonene-Mineral-Oil-and/10.3954/JAUE21-04.full
Demirel, N., and W. Cranshaw. 2006. Permethrin treatment of pollination bags as a protecting from false chinch bug, Nysius raphanus (Howard) (Hemiptera: Lygaeidae), injury to canola in Colorado. Crop Protection. 25(9): 1062-1064.
Available https://colostate.primo.exlibrisgroup.com/discovery/fulldisplay?docid=cdi_elsevier_sciencedirect_doi_10_1016_j_cropro_2006_01_009&context=PC&vid=01COLSU_INST:01COLSU&lang=en&search_scope=MyCampus_FC_CI_PU_P&adaptor=Primo%20Central&tab=Everything&query=any,contains,false%20chinch%20bug
Demirel, N, and W. Cranshaw. 2006. Plant Yield Response to Artificial Infestation of the False Chinch Bug, Nysius raphanus, Confined on Spring Canola. Phytoparasitica. 34(5): 477-485. Available https://link.springer.com/content/pdf/10.1007/BF02981202.pdf
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
Warrick, G. 2012. Effects of False Chinch Bugs on Spiny Saltbush in the San Joaquin Valley, California. Southwestern Entomologist. 37(3): 335-339. Available https://bioone.org/journals/southwestern-entomologist/volume-37/issue-3/059.037.0309/Effects-of-False-Chinch-Bugs1-on-Spiny-Saltbush-in-the/10.3958/059.037.0309.full