chinch bug

a small lygaeid bug, Blissus leucopterus, that feeds on corn, wheat, and other grains.

[1775-85, Amer.]

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▪ insect

 (Blissus leucopterus), important grain and corn pest belonging to the insect family Lygaeidae (order Heteroptera). Though a native of tropical America, the chinch bug has extended its range to include much of North America. It is a small bug, not more than 5 mm (0.2 inch) long. The adult is black with red legs; the white forewings have a black spot near the outer edge. In spring, adults that hibernated during the winter migrate from clumps of weeds to a wheat or other grain field. Each female then deposits about 300 to 500 cylindrical, yellow eggs on the roots, lower leaves, and stems of the grain. Reddish nymphs with a light band across the back emerge from the eggs after one or two weeks and immediately begin to suck the plant's sap. They grow rapidly, becoming dark and molting five times in about 40 days. When the wheat becomes too hard to suck or when harvest begins, large numbers of chinch bugs migrate—by crawling or flying, depending on the stage of development—to another grain field in search of food and a place to deposit eggs for a second generation. In autumn the second-generation adults fly to clumps of grass or some other sheltered place and hibernate during the winter.

      Control methods include the destruction of hibernating sites, controlled planting of cereal grains, and use of immune and resistant crops. Measures effective in small areas include spraying and trapping the migrating bugs in chemical barriers. Since chinch bugs prefer sunshine, planting shade crops, such as cowpeas or soybeans, creates an unfavourable environment. Wet weather promotes the growth of a fungus that kills them.

      The hairy chinch bug (Blissus hirtus) does not migrate. This short-winged insect, sometimes a lawn pest, is controlled by fertilizing, watering, and cutting grass. The false chinch bug (Nysius ericae) is brownish gray and resembles the chinch bug. It feeds on many plants but is rarely an important crop pest.

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