CHINCH BUG

Background shows chinch bugs leaving maturing wheat to feed on young corn. A, Life stages of the insect (greatly enlarged); a, eggs in wheat sheath; G. adult bug; c, red nymph; and d, black nymph.

CHINCH BUG

The chinch bug is mainly a pest of corn and sorghums, but it may injure small grains and other grass crops. As adults the bugs hibernate chiefly in clump-forming native prairie grasses or, lacking them, in hedgerows, bushy and grassy fence rows, and the south and west edges of woodlands. The spring flights of overwintering bugs occur on sunny days when the temperature remains at 70 F. or more for several hours. They usually fly to fields of small grains but in some years may go directly to early-planted corn or sorghums. Each female lays an average of 200 eggs over a period of 3 to 4 weeks. The eggs are deposited behind the leaf sheath, in the ground around the plants, or on the roots. They hatch in 7 to 14 days.

As the small grains ripen, the young bugs move into adjacent fields of young corn, sorghum, or other grass plants. In the northern section of their habitat, the migration is on foot; in the southern area the adults may fly. Mating takes place again, and the eggs of a second generation are deposited on the host plants. During the warm fall afternoons the chinch bugs fly to their winter quarters. There are two or more generations a year, depending on the length of the growing season.

Control: Grow immune or resistant crops. Plant nongrass crops adjacent to fields of small grains. Growing of legumes among small grains and corn often helps to produce shade and dampness in which the chinch bugs thrive. Plant strains of corn and sorghums that are resistant to the attacks of chinch bugs. No immune strains are available, but strains differ in their resistance and tolerance. Consult your county agent or your State agricultural experiment station on the best hybrids to plant in your locality. Modify farm practices to reduce infestation. Chinch bugs will reproduce faster on barley than other small grains and the planting of this crop (especially spring barley) should be avoided when there is a prospect of an abundance of chinch bugs. Anything that can be done to produce a thick, vigorous growth of small grain such as thorough tillage, ample fertilization, and timely seeding helps to reduce injury from the bugs. In the South, plant sorghums as early as practical; if possible, do not plant corn until after the chinch bugs have migrated from winter quarters. Several types of barriers are effective in preventing the chinch bugs from crawling from small grain into adjacent corn and sorghums. The best barriers include a narrow band of either a repellent such as coal-tar creosote oil or insecticidal dusts containing DDT or dinitro-o-cresol. Detailed instructions for building chinch bug barriers may be obtained from your State agricultural experiment station. Use insecticides on lawns, valuable grasses, grains or where the bugs are confined to the border rows of corn or sorghums. Insecticide formulations containing nicotine, rotenone, sabadilla, DDT, chlordane, and toxaphene have given good results.

Consult your county agent or State agricultural experiment station for current recommendations for your locality.