CHINCH BUG, a North American heteropterous insect (Blissus leucopterus) occurring in most parts of the United States, but particularly destructive to grain crops in the valleys of the Mississippi, Missouri and Ohio rivers. It is probably the most destructive native insect, and has frequently damaged crops to the extent of many million dollars in a single year. It was first noticed in North Carolina, at the close of the Revolutionary War, was first described and named by Thomas Say in 1831, and with the growth of agriculture in the Middle West, soon became a pest of the first importance. In 1871 it damaged the wheat, oat and barley crops of Illinois, Iowa, Indiana, Nebraska, Missouri and Kansas to the estimated amount of $30,000,000. The loss in 1887 to maize, wheat and oats was estimated at $79,000,000.
Originally the chinch bug fed upon wild grasses, but when the cultivation of wheat reached its native haunts it multiplied enormously. It is a small black and white insect, about - in. long, and when full grown has a long-winged and a short-winged form. The adult bugs hibernate in sheltered places, usually clustering about the roots and bases of grassy plants. In the spring they lay their eggs behind the lower blades of the grain or in the ground around the plants. The young, when hatched, are bright red in colour, and begin at once to suck the sap of the plants.
They grow rather rapidly and shed their skins five times, the adult being the fifth stage. By the time the majority are full grown, or even before, the wheat has become too hard to suck, or harvest begins, and they are then compelled to migrate in search of food.
The cropping systems prevalent in the Middle West offer at once new sources of food. In seasons of abundance the bugs march in throngs from the wheat to the maize. The full-grown individuals do not generally take wing, but walk along the ground. Occasionally, however, at this time they take wing and scatter. There is generally a second generation on maize, the adults ap pearing in the autumn and flying back to their winter quarters at the roots of wild grasses or other sheltered places.
The chinch bug is most susceptible to weather conditions, and with wet weather in the late spring and the end of July the young are either destroyed by the water or develop an epi demic fungous disease. In dry weather, however, they flourish. Seasons in which they occur in great numbers are rarely consecu tive. Outbreaks have lasted for two or three years, but, in the same locality, years of abundance are apt to be separated. Serious damage may be obviated by proper cropping of farms, reducing the acreage of small grains and using the land for immune crops. Resistant varieties of grains have also been found. At the time of migration, millions may be destroyed by barriers of various kinds, including ditches, and by using kerosene or creosote. Tak ing advantage of the hibernating habit, the burning of old grasses, particularly the so-called bunch-grass along roadsides, when or ganized and done co-operatively, destroys the bugs wholesale and often has the good effect of preventing serious losses during the following summer. Calcium cyanide in dust form has also been sometimes used. But community burning of winter grass seems to be, on the whole, the most feasible means of control.
(L. O. H.)