Chinch bugs are a complex of three different species within the Lygaeidae family. They have piercing-sucking mouthparts and they feed on the sap of grass plants. They reside in the thatch area of the turfgrass stand and prefer to feed on the lower leaf sheath and crown area of the plant. The chinch bug can be a major insect pest on home lawns throughout the country. The hairy chinch bug (Blissus hirtus) is the most common species in the Northeast. The hairy chinch bug prefers bentgrasses, but will attack many other lawn grasses as well. The adult chinch bugs are about 3 to 5 mm (1/8 to 1/5 inch) in length and black with white markings on the wings. The wings rest flat over the back of the insect and there is a black spot between the wings. Adults may be long-winged or short-winged. There are five nymphal instars of chinch bus ranging in size from 1 to 3 mm (1/32 to 1/5 inch). The first two nymphal instars are red, with a white band across their abdomen, while the third and fourth instars are orange with wing pads just beginning to appear. The fifth instar is black with wing pads easily visible.
The chinch bug inserts its straw-like mouthparts into the plant tissue and sucks out the plant juices while injecting chemicals into the plant which clog the vascular system. The area around the feeding puncture usually turns yellow. Damaged areas first appear as small, irregular patches which enlarge as the insects spread. Chinch bugs are most damaging in open, sunny areas.
Chinch bugs spend the winter as adults in partially protected areas (under shrubs or around foundations of houses). As the weather warms in the spring, adults move into open areas, where females begin laying eggs. Fifteen to 20 eggs per day are deposited for two to three weeks. The eggs hatch in one to two weeks, and the nymphs begin to suck the juices from host plants. It takes 30-90 days to reach adulthood. There are two generations per year, with a partial third generation in unusually warm summers. There is considerable overlap of generations, and all stages can be found during the summer.
Examine the grass in the marginal areas of injured patches, not in the clearly dead grass. Spread the grass gently with your fingers and look in the thatch, near the soil surface. Chinch bugs are usually very active in the summer, so you will be able to see them scurrying around, especially on warm summer days. An alternative method of detecting chinch bugs is to remove both ends of a large tin can, such as a coffee can. Soften the soil a little with water, and insert one end of the can into the ground at least 5 to 8 cm (2-3 inches) deep, leaving at least 10 cm (4 inches) of the can above the ground. Fill the can with water and wait about five minutes. If chinch bugs are present, they will float to the surface of the water, where you can count them.
In many instances, chemical control of chinch bugs is not necessary. Studies in Michigan have demonstrated that lawns which receive adequate amounts of water throughout the summer (preferably weekly deep watering's) are able to tolerate relatively high populations of chinch bugs without sustaining damage. In addition, many lawns have natural populations of predators, such as ground beetles or "big-eyed bugs," which can keep chinch bug populations from getting out of hand. Insecticide applications sometimes have very adverse effects on these predators, causing the chinch bug populations to develop more rapidly in subsequent years. Plant resistance has also been reported for a number of turfgrass species and cultivars. Research has demonstrated strong resistance of endophyte-enhanced turfgrasses to the hairy chinch bug.
Turfgrass managers usually control chinch bug populations after major damage has occurred. To avoid this problem in areas with habitual problems, an April to mid-May insecticide application will control the overwintering females and subsequent generations during the summer. Reinfestation may occur from adjacent areas, but this process is slow and may require an additional year or more. This adult treatment must be made before egg laying occurs. As with any pesticide application, be sure to read the label and apply the material at the specified rate. Avoid mowing the area for two or three days afterward.