Turfgrass Entomology (chinchbg)
|The two most important hemipteran (true bugs) pests of turfgrasses in Nebraska are the chinch bug, Blissus leucopterus leucopterus, and a new species called the "buffalograss" chinch bug, Blissus sp. The chinch bug, known mainly for its damage to field crops, also feeds on a variety of turfgrasses, including Kentucky bluegrass, perennial ryegrass, fescue, bentgrass and zoysiagrass. The buffalograss chinch bug however, has been observed only on buffalograss. Neither chinch bug species has been a major problem in Nebraska.Description and Life History
The immature stages of both chinch bug species are similar in appearance. First instar nymphs are tiny (about 1/64 inch long), bright red insects with a white band across the abdomen. As nymphs mature (there are five nymphal stages), their color changes to orange-brown and finally to black. Adults are black and about 1/10 inch long (females are slightly larger than males). The adult "crops" chinch bug is black and white and has fully-developed wings which fold over the back and extend to the end of the abdomen. During most of the season, however, buffalograss chinch bug adults appear wingless, although very short "vestigial" wings are actually present. Flight activity is seldom observed. Both species overwinter as adults in and around the turf area. In the early spring, adults emerge from overwintering sites and mate. Females insert their eggs behind leaf sheaths in the crown of plants and on underground roots in the surrounding soil. Eggs hatch during mid to late May. Nymphal development takes about a month. Adults of this first summer generation begin to appear in early July. All adult "crops" chinch bugs and a significant proportion of the buffalograss chinch bugs in this generation have fully-developed wings and are capable of dispersing to new feeding sites. The second summer generation eggs hatch during mid to late July, and complete development in September and early October. Adults of this generation begin moving to overwintering sites with the onset of lower fall temperatures.General Symptoms of Chinch Bug Damage to TurfgrassBoth nymph and adult chinch bugs feed by sucking juices from the leaves and stems of the turfgrass. During the feeding process, a salivary toxin is injected into the plant which disrupts the translocation of water and nutrients, resulting in wilt and discoloration of plant tissues. Damage appears as patchy areas in the turf which turn yellow over time. As feeding progresses; the turf dries out and turns brown. At higher infestations levels, chinch bug feeding can result in severe thinning or even death of the turf stand. Damage is usually the heaviest in sunny locations during hot, dry periods and is often mistaken for drought stress.Sampling Techniques
Buffalograss Chinch Bugs,
Winged & Wingless
The most effective method of confirming a chinch bug infestation involves removing both ends from a 2 lb. (9-inch diameter) metal coffee can, pressing one end about 2 to 4 inches into the soil in an area of suspected infestation and filling the can with water. Chinch bugs will float to the surface in 5 to 10 minutes. Chinch bugs can also be detected by sprinkling 1/4 cup of lemon-scented household detergent mixed in two gallons of water over one square yard of turf and counting the insects as they crawl to the surface. Be certain that chinch bugs and not beneficial big-eyed bugs are being counted. Big-eyed bugs can be distinguished by chinch bugs by their gray to black oval bodies and large, conspicuous eyes.Management StrategiesThe best defense against chinch bugs involves the use of sound cultural practices designed to maintain turfgrass stands in optimum condition. Since these insects seem to prefer turf areas high in thatch and organic debris, cultural and mowing practices that minimize thatch accumulation should discourage initial invasion and may also help reduce chinch bug problems if and when they arise. Several turfgrass species and cultivars with natural or endophyte-enhanced resistance to chinch bugs are now available. These have proven very effective in reducing chinch bug damage. Information on adapted insect-resistant turfgrass species and cultivars can be obtained from your local University of Nebraska Cooperative Extension office.Insecticidal ControlIf chinch bugs exceed 20 per square foot of turf (8 to 10 per 9" diameter cylinder) and feeding damage is evident, control is probably justified. Before treatment, the turf should be mowed and the clippings removed. This will minimize interception of the insecticide by the turf canopy. Immediately following application, irrigate the treated area with 1/8 inch of water to wash the insecticide off grass blades and down into plant crowns and thatch where the chinch bugs are feeding. In turf stands where numbers are especially high, two insecticide applications may be required to achieve satisfactory control both chinch bug generations. These treatments should be applied while chinch bugs are small. This would normally be during mid-June for the first generation and late-July through mid-August for second-generation chinch bugs.
Coffee Can Detection
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