Small Grains and Forage

Chinch Bug

Blissus leucopterus leucopterus Say

Appearance and Life History

Chinch bug - Adult and nymphs Adults and nymphs
Photo by University of Nebraska

During years of normal to high levels of spring and summer rainfall, a fungal disease usually keeps chinch bug populations at subeconomic levels. However, the disease may not develop during dry periods. Following several dry seasons, chinch bug populations can expand to outbreak levels, causing considerable damage to a number of small grains, as well as grain sorghum and corn.

The adult chinch bug is about 3/16 inch (4.7 mm) long, with a black body and white forewings. Its white wing covers are each marked by a triangular black patch at the middle of the outer margins. The adult's legs are red to reddish-yellow.

A newly hatched bug is small and bright red. It develops through five nymphal stages before reaching adulthood. During the first four stages, it is red with a white band across its back. The fifth instar nymph is mostly black in color with a white spot between its developing wings.

The chinch bug overwinters as an adult, usually at the base of clumped grasses. Once daytime temperatures reach 70°F (21°C) during the spring, the mature bug flies into a small grain fields. The female deposits eggs behind lower leaf sheaths and at the crowns of plants, especially where stands are thin.

Time of Attack to Small Grains - Chinch Bug

Damage

Chinch Bugs - Adults and nymphs Adults and nymphs
Photo by University of Nebraska

Both adults and immature chinch bugs cause crop injury by sucking plant juices. As they feed, they also inject a toxin into the plant tissue. Chinch bugs may feed at the crowns or just below the soil surface on the roots of small plants. On large plants, they are found feeding on stems behind the leaf sheaths. Heavy spring infestations in wheat or barley can reduce yields and, when chinch bugs occur in high numbers, plants may be killed.

Once the crop has matured and the plants dry, both adults and nymphs migrate to adjacent grain sorghum or corn fields where they continue to feed.

Sampling Method

If one observes chinch bugs or their damage, carefully examine 20 stems in each of 5 areas of the field. Record the percentage of stems that are infested and rate the population as slight, moderate, or severe. Also note the stage of development of the plants.

Management Guidelines

Small Grains Insect Control Recommendations: E-series 220-W (PDF)

Treatment is usually recommended only if the plants are under stress, wilting, or a majority of the plants in an area are infested. Spot treatment may be possible to control a localized damaging population.

If control is necessary, contact your state Cooperative Extension Service or click here for control materials and rates.