(frit flies), a genus of grain flies. There are several species, although the exact number is not known. Each species is usually injurious to one specific grain. The most common species are O. frit, which usually infests oats; O. pusilla, which infests barley; and O. vastator, which infests spring wheat. The last two species also infest winter rye, winter wheat, corn, and some herbs. The insects are widespread in regions where grains are cultivated. The body is black and measures 1.5–2 mm in length. Two or three generations are produced annually in the north, and as many as five in the south. The flies emerge in late April in the south and in late May or early June in the north. The eggs are deposited on young plants with no more than two or three leaves or in the spikelets. The larvae feed inside the stem on the embryo of the spike or on the developing caryopsis. The stems wither, and the central leaf dries up. Infested corn plants branch intensively, many stems become twisted, and the number of ears decreases sharply. The insects winter, usually in the larval phase, in the stems of perennial grasses and on the shoots of winter crops.
Measures to combat the flies include scuffling of the stubble, early fall-winter plowing of grain fields, early sowing of spike crops, sowing of corn and winter crops at the optimum time, early top-dressing of shoots with inorganic fertilizers, and treating of seeds and grain crops with pesticides.
REFERENCESShapiro, I. D. Shvedskaia mukha—vreditel’ kukuruzy i mery bor’by s nei. Leningrad-Moscow, 1962.
Vrediteli sel’skokhoziaistvennykh kul’tur i lesnykh nasazhdenii, vol. 2. Edited by V. P. Vasil’ev. Kiev, 1974.
I. D. SHAPIRO