| Popis: |
Many insect species are not adapted for surviving the harsh winter temperatures of the midwestern United States, and they must recolonize the region annually. Several of these migratory species pose a threat to midwestern agriculture. For example, three of the primary field crops (corn, soybeans, alfalfa) in the Midwest are attacked by migrating pests or their progeny. Corn frequently is infested by the black cutworm, Agrotis ipsilon (Hufnagel), which is considered a serious, although sporadic, pest. Soybeans are subject to colonization by the green cloverworm, Plathypena scabra (F). This pest, which is also sporadic, has been known to defoliate soybean crops during outbreaks. Alfalfa plantings in the Midwest are attacked annually by migrating populations of the potato leafhopper, Empoasca fabae (Harris). Feeding by this pest can severely limit the yield and quality of alfalfa as a forage crop. |
