The hairy chinch bug (Blissus leucopterus) can be a serious lawn
pest. It is a tiny insect that grows from egg, to nymph (resembling
an adult), to an adult (less than 4 mm long and 1 mm wide). Nymphs
are orange-red in color changing to black. Adults (male and female)
are black with white wings and two tiny black spots.
In autumn, adults seek shelter where they spend the winter. In late spring they move into the grass to feed and mate. Females can lay hundreds of eggs, attaching several to the base of grasses. Nymphs emerge in early summer, and mature in relation to temperature (not calendar dates), becoming adults early in July or later in August. Eggs are laid and second generation nymphs emerge; however most will not mature in time for winter.
Chinch bugs (adults and nymphs) feed exclusively on grass and grass-type crops using their piercing mouthpart to penetrate the plant and suck on its fluids. Damage is seldom noticed when a few chinch bugs are feeding. When large numbers congregate, damage will appear suddenly and in a circular pattern; as feeding continues, the irregular pattern of dried-out dead grass enlarges. Symptoms of chinch bug damage can be mimicked by other causes including hot temperatures, drought, porous (gravelly) soil, scalping, dog urine, and fertilizer burn. If chinch bugs are suspected, go to the fringe of live and dead grass; part the grass with your fingers and look closely at the soil-surface for clusters of chinch bugs. Another method is to use a large open-ended coffee can. Firmly push one end into the soil and fill the can with water, adding more as needed for a period of 10 minutes; if more than 10 chinch bugs float to the surface you have proof. Also, take notice of how fast the water drains through the can. Rapid water loss indicates that the soil is incapable of holding water, which is a problem more serious than chinch bugs. Poor quality soil will not support healthy grass, and throwing fertilizer at it will not fix the problem (too much fertilizer can encourage chinch bugs).
Chemically treating the lawn seldom works as a long-term solution. Studies have proven that chinch bugs become resistant to chemical pesticides. Although new trends in pest management are developing, the best approach is to modify soil conditions and cultural practices. Soil (minimum depth 4”) must be balanced with the right amount of minerals, organic matter, air and water; and the soil pH should be around 7, usually requiring annual applications of lime (soil testing is recommended). Dense grass cut no shorter than 3 inches in height shades the soil, reduces soil temperature, increases soil-level humidity and inhibits weed growth. Conditions favorable for healthy lawns are not favorable to chinch bugs. Furthermore, chinch bugs can be managed with the help of other insects that feed on them, for example, big-eyed bugs and pirate bugs, which are similar in appearance and often mistaken for chinch bugs. Beneficial insects, other predators and natural diseases are abundant on pesticide fee lawns. Lawns containing a mixture of clover and other plants generally require little maintenance, endure far more stress, and are apt to support a multitude of beneficial organisms.
The hairy chinch bug can be a serious lawn pest, but it need not be when a healthy lawn starts from the ground up and grows in balance with the soil and other organisms.
Nancy Hudson, Research Technician
Nancy is undertaking graduate studies at Memorial University of Newfoundland under the supervision of Dr. Peggy Dixon and is a research technician in the Chinch Bug Research Project.