Chinch Bugs

Several chinch bug species can cause economic damage to turfgrasses in North America. The Hairy chinch bug (Blissus leucopterus leucopterus) can be a frequent pest of fine fescue and Kentucky bluegrass found in home lawns and on golf courses in Pennsylvania. Chinch bug populations frequently go unnoticed because of their small size and coloration, which blends in with turfgrass and thatch.

Chinch bugs undergo paurometabolus or gradual metamorphosis. Immatures (“nymphs") and adults possess a piercing-sucking mouthpart (“stylet") that allows them to draw fluids from the turfgrass plant, which results in affected plants appearing wilted. This feeding may also inject toxins into the vascular system.

Chinch bug damage is often mistaken for drought or disease and is most severe in south-facing areas with excessive thatch.  Populations often increase throughout the year, with severe infestations containing as many as 150 to 200 insects per square foot.  

Identification

Adults

An adult hairy chinch bug is about 1/6 inch long, has a gray-black body with fine hairs, white wings, and reddish legs. Half-hardened forewings (hemielytra) are folded over one another creating a triangle (scutellum) behind the pronotum. The outer margin of each forewing has a small, black, triangular spot. Both long-winged and short-winged (brachypterous) adults may be observed in the same population.

Eggs

In the spring female chinch bugs begin laying eggs. The eggs are pushed into protected places, often being found between the leaf sheath and the stem. Females lay only a few eggs for several weeks. Eggs hatch in about 2 weeks. The eggs are small and oval-shaped, with a blunt end from which four small projections extend. The eggs begin as a pale white color and turn amber and eventually red before they hatch.

Nymphs

Young nymphs initially appear orange to brick-red with a transverse white band across the back. As the young mature, they turn gray and then black. Wing pads- or non-functional wings- are present on the 4^th and 5^th instar nymphs.  

General Life History

Adults overwinter in leaf litter and dense thatch areas. Two generations typically occur each year, and a partial third generation occurs during years with long summers. Adults usually remain in their overwintering sites until spring temperatures reach 50°F. Then adults begin to disperse, mate, and lay eggs. Egg laying continues throughout their adult life. An adult female may produce an average of 300 eggs over 40 to 50 days. The eggs are deposited in leaf sheaths and in the ground on roots of host plants. The eggs hatch in 1 to 2 weeks, and the nymphs complete a series of five molts before maturing into adults over a period of 4 to 6 weeks. The new adults lay eggs from mid-July through late August. Second-generation nymphs hatch from the eggs and complete development from September through October. When the cool weather arrives, adults seek overwintering sites.

Hairy chinch bugs can develop on fine leaf fescues, perennial ryegrass, bentgrass, and Kentucky bluegrass. Infestations frequently occur in turfgrass with thick thatch that is exposed to full sunlight during periods of hot, dry weather. Chinch bug damage is often less noticeable during the spring and early summer. Damage frequently appears from early July through September when the insects are actively feeding. Chinch bug damaged areas often coalesce into large patches of dead, brown grass. The suggested economic threshold for chinch bug is 15 to 25 insects per square foot.

Monitoring

Visual inspection of healthy turfgrass bordering the dead turfgrass is one sampling method for chinch bugs. The fast-moving adults and nymphs can be seen scurrying about at the base of grass stems and aggregating in groups. However, these insects frequently blend in with the thatch and go unnoticed. On a sunny day, one can notice adults crawling across driveways, sidewalks, and/or over foundation block walls. Hairy chinch bugs can be detected by using a flotation can. This involves removing both ends of a one-gallon metal can to create a cylinder, driving it several inches into the soil, and filling it three-quarters full with water. Continue to add water until the water level stabilizes (soil saturation). Stir the duff at the bottom of the cylinder to dislodge chinch bugs located in the thatch. The disturbed chinch bugs soon float to the surface. Count the number of adults and nymphs floating to the surface over a 10-minute period, but do not confuse them with the beneficial big-eyed bug (Fig. 3). Refill the can if the water soaks into the ground before the end of the 10-minute sampling interval. Research suggests that 15 to 25 chinch bug life stages per square foot may warrant control, especially when chinch bugs are actively feeding during the summer months.

Management

Nonchemical – Cultural

Minimizing thatch accumulation may discourage initial infestations and may help reduce chinch bug problems in the future.  Additionally, incorporating endophyte-enhanced turfgrasses into the stand can provide resistance to chinch bugs. Endophytes are usually beneficial fungi that live between the cell walls of grass plants. In most instances, fungal endophytes produce alkaloids, which give enhanced resistance to insects and disease. Currently, endophytes occur in tall fescue, fine fescue, and perennial ryegrass seed. Follow all label directions regarding where you use endophyte-enhanced seed since you do not want to negatively impact the health of livestock, which is often referred to as endophyte toxicosis. In some instances, fertilization and irrigation can assist in masking chinch bug damage

Biological Control

The big-eyed bug is the primary predator of hairy chinch bug nymphs and adults. The chinch bug's head is relatively small, triangular, and carries two small eyes, whereas the big-eyed bug is solid gray or brown, more robust, blunt head, and of course, equipped with big protruding compound eyes. In some instances, hairy chinch bug nymphs and adults will be covered with white, cottony-like material, which is the entomophagous fungus Beauveria bassiana (Blas.). Unfortunately, this fungus rarely attacks enough chinch bugs to suppress populations below their economic threshold.

Chemical Control

Conventional insecticides can suppress nymphs and adults throughout the summer when they are actively feeding on turfgrass. You should sample the area to determine chinch bug density prior to applying any control measure. Products that have systemic activity (e.g. neonicotinoids) or combination products (i.e. insecticides with two active ingredients) are generally recommended in spring when adults are present and beginning to lay eggs. The residual activity of these products ensures that the nymphs that hatch from eggs at the time of application will acquire the toxin. Contact insecticides (pyrethroids, organophosphates) can be used to curatively treat populations (i.e. after damage has been realized). This strategy is effective in late summer-early fall when most of the population are adults. Follow all specific label directions.

Warning

The impact of several classes of insecticides on pollinating insects such as honey bees and native bees is a cause for concern. Because they are systemic chemicals absorbed into the plant, some of these products can be present in pollen and nectar, making them toxic to pollinators that feed on them.

Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.