For the second year in a row (that we’ve noticed), soybean aphid has been present in North Carolina. Soybean aphid is the most important insect pest of Midwest soybeans, but is not very prevalent in North Carolina. Soybean aphid is better adapted to northern climates and it’s overwintering host, buckthorn, is not commonly known in the state.
Last year’s cool and cloudy summer must have created good conditions for soybean aphid, since it could be found throughout the state. This year, a NCSU Entomology graduate student, Brad Fritz, noticed soybean aphid in the Sandhills. Last year, a few fields were at treatable levels (250 aphids per plant) a bit west in the Piedmont.
Pure speculation here, but maybe buckhorn is more prevalent here than other areas. Certainly the climate must have something to do with their presence and, perhaps, spread from areas where they are more common. At the most, soybean aphid has seemed to remain more of a curiosity in the state since fields at or near threshold are rare.