Chinch Bug Management in Residential Lawns

by Jesse Benelli, PhD, Envu

Chinch bugs are above ground pests that feed predominately during the summer months. Chinch bugs prefer to feed on Kentucky bluegrass and fescue lawns. However, damage can occur on other types of bluegrasses, bentgrasses, and ryegrasses. Damage tends to be most severe on recently sodded Kentucky bluegrass lawns. The two primary species of chinch bugs are the hairy chinch bug and the southern chinch bug. In New Jersey, it is the hairy chinch bug that is most problematic on cool-season turfgrasses. Regardless of the chinch bug species, all chinch bugs produce five nymphal stages before becoming mature adults. All nymphal stages as well as chinch bug adults are capable of damaging turfgrasses.

First instar nymphs are orange with a beige stripe that runs horizontally across the mid-section. Early instar nymphs are incredibly small, with most of them being just under 1 mm in length. As nymphs mature in size, the orange color gradually gives way to a more of a dark brown to grey appearance. It is not until the 5th instar stage when wing pads are fully distinguishable, and the overall color of the chinch bug is black. Fully mature chinch bug adults will either be short-winged adults (cannot fly) or long-winged adults (can fly) and will be approximately 3 mm in length. Despite the ability to fly, most long winged adults will preferentially move along the surface of the ground as their preferred method of travel.

Chinch bugs overwinter as adults in late fall. Common overwintering sites include the turfgrass thatch, mulch beds, and beneath landscape rocks. In the spring, chinch bug adults migrate into lawns to begin feeding and mating. Females lay eggs when daytime temperatures exceed 60°F. Each female can lay up to 200-300 eggs each reproductive cycle. In the Midwest and Northeast, the eggs of chinch bugs may hatch in mid-to-late May depending on the region and weather.

Chinch bug nymphs and adults have piercing-sucking mouthparts that injure turf by withdrawing sap from leaf, sheath, crown, and stem tissues. During feeding, chinch bugs inject salivary toxins into the plant causing coagulation within stem and leaf tissue, which affects the plant’s ability to transport water and nutrients. Initial symptoms of chinch bug feed- ing include reddish purple discoloration of the leaf blade margins. As damage progresses, the affected leaves turn yellow, and thinning can be observed. As feeding intensifies, plants begin to turn straw color and do not respond to irrigation or fertilization inputs. If left untreated, large swaths of turf will decline and death can occur. Turfgrasses grown on south facing slops that receive full sun are at most risk of decline.

Chinch bugs are most active during the early afternoon hours when it is sunny and warm. Adults can be seen in the spring on grass blades and nearby structures such as patios, decks, foundation walls, and fencing. Nymphs are much harder to see. Nymphs will be present from mid-to-late June through August. Nymphs tend to feed very close to the base of the plant stem. In late spring and early summer, it is important to get close to the ground and peel away the thatch material to scout for chinch bug nymphs.

An effective strategy for chinch bug scouting and monitoring is through a modified flush technique. Use a plastic or metal cylinder (such as a soup or coffee can) and remove both lids to the container. Lightly pound the canister into the ground with a rubber mallet so that the container is approximately 2 inches in the ground. Fill up the canister with water and keep refilling the canister to ensure water isn’t draining too quickly. After 30 seconds, chinch bug nymphs and adults will float to the surface. Count of the number of chinch bugs that have surfaced. A common threshold to determine if a spray application is necessary is approximately 5-8 chinch bugs per 6-inch diameter coffee canister. This sampling should be done at several locations in the lawn.

The use of monitoring growing degree days (GDD) could also be employed. Several variations of growing degree day models have been developed in North America. The most used base temperature is 7°C. Using this base temperature, peak egg development occurs at 187 – 340 GDD and 1st instar nymphs are observed between 250 – 500 GDD. Peak damage caused by 3rd and 4th instar nymphs occur between 600 – 1000 GDD.

Fertility. Maintain adequate nitrogen fertility during spring, summer, and fall. Lawns deficient in nitrogen will have less energy and have a lower recuperative potential to tolerate chinch bug feeding. Late summer or fall fertilization can be effective in recovering compromised lawns.

Irrigation. It is important to irrigate lawns to prevent wilt stress during the summer months to prevent further turfgrass decline. Turf grown on south facing slopes in full sun may require more water than areas grown in shade.

Overseeding. Introducing endophyte-enhanced grasses will improve the lawn’s tolerance to chinch bug activity. Endophytes are non-pathogenic fungi that can allow for reduced inputs on residential lawns and can help reduce chinch bug damage.

Mowing. It is best to cut and maintain the lawn at a height of 2 – 3 inches height during the summer months. It is important to mow at the rate of growth. The rule of thumb is to not remove more than 1/3rd of the leaf tissue when moving. Maintain sharp blades to prevent a ragged cut that could result in moisture loss and decreased turf quality.

Populations of newly emerged chinch bug nymphs can rise very fast in the spring after the onset of warmer weather. Routine scouting and monitoring are critical to help time your insecticide applications. The best time to scout for chinch bug activity is when daytime conditions are warm and sunny. An insecticide application is usually warranted if chinch bug populations exceed 1520 nymphs and adults per square foot.

Contact insecticides, such as Barricor ®️ SP (a new generation pyrethroid), should be applied when chinch bug nymphs are most active (such as a warm and sunny day). Higher rates should be used when chinch bug populations are extremely high. Tank mixing Barricor SP with a systemic insecticide (such as MeritTM or Tetrino®️) will help provide greater residual control of chinch bugs and offers a broader spectrum control of other insect pests such as white grubs and billbug larvae.

The number of insecticide applications to control chinch bug populations season long will depend on the region and weather. In most years a single well- timed application will provide adequate control season long. However, a second insecticide application may be needed during if there is sustained heat and drought in late-summer and early fall.

Dr. Jesse Benelli is based in Greenville, SC, and is a Green Solutions Specialist for Envu covering the Southeast region. He is a graduate of the Pennsylvania State Turfgrass Program and received his MS and PhD degrees from the University of Tennessee. Prior to joining Envu, Dr. Benelli was the Director of Turfgrass Programs for the Chicago District Golf Association where he provided agronomic consulting with more than 400 member clubs throughout the region.