. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. INSECTS AFFECTING FIELD CROPS 493 contend with. The insects hibernate in old corn stalks, dead leaves, clumps of grass or other sheltered places in the field or roadside. As soon as the grasses or grains begin to grow they begin feeding on them and lay their eggs, from which the first brood of young soon issues. They may do serious injury to the wheat or other small grains before the crops ripen. About the time the wheat is ready for harvest the chinch-bugs migrate to oats or young corn. Fortunately, they do not f
. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. INSECTS AFFECTING FIELD CROPS 493 contend with. The insects hibernate in old corn stalks, dead leaves, clumps of grass or other sheltered places in the field or roadside. As soon as the grasses or grains begin to grow they begin feeding on them and lay their eggs, from which the first brood of young soon issues. They may do serious injury to the wheat or other small grains before the crops ripen. About the time the wheat is ready for harvest the chinch-bugs migrate to oats or young corn. Fortunately, they do not fly when making these migrations, but crawl slowly from field to field. The eggs from which the second brood are to hatch are laid in the corn. The young of this brood be- come mature late in the fall and seek out suitable places to hibernate. If corn is not available the whole season may be passed on grasses. Many years ago it was discovered that the chinch-bugs were attacked by a fungus disease that sometimes very effec- tively controlled them. When infected bugs are taken into the laboratory and placed in boxes with healthy bugs, the latter soon become infected. These infected bugs may then be sent into the fields and placed on badly infested plants. In this way the disease rapidly spreads, and when the climatic conditions are right it soon destroys most of the chinch- bugs in the field. But this method of control has not been wholly satisfactory because in cool and dry weather the disease does not spread fast enough. Clean culture is of prime importance. If the adult bugs that are hibernating in the fields or in grasses by the roadside and fences are destroyed by burning, there will be no injury in the following spring. When the insects are migrating from the wheat to the corn they may be effectively checked by barriers of dust or coal tar. The dust barrier is made by plowing and thoroughly pulverizing a narrow strip of ground. FIG. 232. — The chinch-bug, Bliss us leu copt
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