Hairy chinch bug,
Blissus leucopterus hirtus
Adults of hairy chinch bug are about 3.5 mm (0.1 inches) long and 0.75 mm wide, and males are usually smaller. The adults have white wings with a black spot on the middle edge of the forewing. Their legs are maroon or dark red and are sometimes described as having a dark burnt orange tint. Adults can be short-winged or have fully developed wings. Adults with reduced wings do not fly.
• Chinch bugs are uncommon in Colorado; however the hairy chinch bug is a documented pest of turfgrass in some parts of the state, including the Denver area and Tri-River counties of the West Slope.
• Hairy chinch bugs are considered “true” chinch bugs and are in the same order as the false chinch bug (Nysius raphanus), which is a pest of mustard plants.
• Hairy chinch bugs tend to prefer feeding on Kentucky bluegrass, fescues, perennial rygrass, bentgrass, and zoysiagrass.
Adult hairy chinch bugs on a grass blade. There are two forms of adults, one with fully developed wings (alate) and one with short, reduced wings. Only the one with fully developed wings is visible in this image. The hairy chinch bug prefers to feed on Kentucky bluegrass, fescues, perennial rygrass, bentgrass, and zoysiagrass. Healthy lawns with adequate watering are typically able to tolerate feeding of hairy chinch bug. Image credit: David Shetlar, The Ohio State University, Bugwood.org
Injury to home lawn caused by the hairy chinch bug. Image credit: David Shetlar, The Ohio State University, Bugwood.org
Bigeyed bugs are a natural enemy of chinch bugs and have a similar appearance. The two insects can be distinguished by the shape and size of the head: bigeyed bugs have much larger eyes than chinch bugs. It is important to distinguish between the two when sampling lawns. Image credit: David Shetlar, The Ohio State University, Bugwood.org
Field sampling for chinch bug (Blissus leucopterus leucopterus). Image credit: Jim Baker, North Carolina State University, Bugwood.org
Life history and habits
Nymphs develop through five instar stages, with each instar characterized by differing size and combination of colors and markings. The first instar is about 1 mm long and the fifth instar about 3 mm long and similar in appearance to adults. First instars have a brown head and thorax and a bright orange abdomen with a white stripe. The second, third, and fourth instars are characterized by a purple-gray abdomen with two black spots. The fifth instar has visible wing pads and a blue-black abdomen with dark spots.
Adults of hairy chinch bug overwinter at the base of grass stems in turf and in the thatch. They overwinter as adults, and in the spring when daily temperatures reach 70°F (21°C) the adults migrate to grain crops and can become established in turf. Females deposit their eggs in the thatch or in the folds of grass blades. A single female can lay as many as 200 eggs over a two-to-three-month period. Egg hatch can take as little as one week when temperatures exceed 80°F (26.5°C), but considerably longer at temperatures below 70°F.
Early signs of feeding injury include irregular patches of turf turning yellow and brown. If left untreated, these patches will continue expanding until the turf eventually dies. Symptoms of feeding injury tend to appear during hot, dry weather, and resemble drought stress, turf diseases, or feeding injury from other insect pests. Feeding of hairy chinch bug can also result in turf with a purplish tint.
Early detection of hairy chinch bug is important for effective treatment. To scout for hairy chinch bug, inspect grass in the margins of injured patches. Look in the thatch near the soil surface by gently spreading the grass with your fingers. Be sure not to look at dead grass within the patch. Hairy chinch bug activity is highest in the summer when they can be seen crawling in grass as well as the foundations of nearby buildings.
Another monitoring method involves the use of a large tin can. Remove both ends and insert one end of the can into soil that has been softened with water. The can should be inserted at least two or three inches in the ground, with around four inches remaining above ground. Once the can is in place, fill it with water and wait about five minutes. Hairy chinch bugs will float to the surface where they can be counted. Generally, control is warranted if more than 25 individuals are found per square foot.
Geocoris spp., commonly referred to as bigeyed bugs, are natural enemies of hairy chinch bug that are similar in appearance and highly abundant. Bigeyed bugs can be distinguished from hairy chinch bug by the shape of the head and size of their eyes – bigeyed bugs have much larger eyes than hairy chinch bug (see images).
Adequately watering lawns generally allows them to compensate for feeding of hairy chinch bug. Some grasses are resistant to hairy chinch bug feeding, including perennial ryegrasses, fine fescues, and tall fescues with endophytes. Endophytic turf should be used for reseeding lawns that have been damaged by hairy chinch bugs. Turf with slight signs of feeding injury can recover with light fertilization and regular watering. Applying too much fertilizer should be avoided since lush turf will be more attractive to chinch bugs. Overseeding is likely necessary in heavily infested lawns with high plant mortality. In lawns that have a thick thatch and a history of chinch bug activity, removing the thatch layer can help limit chinch bug activity for one or two years.
Natural enemies such as ground beetles and bigeyed bugs feed on chinch bugs and suppress their densities. To preserve these natural enemies, insecticides should only be applied as a last resort. The fungus, Beauveria bassiana, can also attack hairy chinch bug and reduce their numbers below damaging levels, especially earlier in the season during cool wet springs.
Preventative treatments are only necessary when the pest is a recurring problem and should only be done after sampling for hairy chinch bug. Lawns can be treated in the spring to target overwintering adults and young nymphs. Insecticides can also be applied after sampling when hairy chinch bug densities appear to reach damaging levels. For more information on insecticidal control of hairy chinch bug, consult the Ohio State University webpage.
Cranshaw, W. (n.d.). False Chinch Bugs. Colorado State University Extension. Available https://extension.colostate.edu/topic-areas/insects/false-chinch-bugs-5-603-2/#:~:text=The%20chinch%20bug%20species%20recorded,counties%20of%20the%20West%20Slope.
Shetlar, D., and Andon, J. 2012. Chinch Bugs in Turfgrass. Ohio State University Extension. Available https://ohioline.osu.edu/factsheet/HYG-2503-11#:~:text=Chinch%20bug%20damage%20is%20usually,insect%20damage%2C%20or%20turf%20diseases.
University of New Hampshire. (n.d.). Hairy Chinch Bug. University of New Hampshire Extension. Available https://extension.unh.edu/resource/hairy-chinch-bug-fact-sheet#:~:text=Monitoring%20%2D%20Find%20an%20area%20of,found%2C%20you%20have%20a%20problem.