Abstract
In Tohoku district, outbreaks of several noctuids have occurred in tame grasslands during the last more than ten years. The following three species may have been immigrants, and the outbreaks were abrupt. The Oriental armyworm, Mythimna separata WALKER, attacked gramineae mainly in early summer. The total area of damaged grasslands markedly fluctuated from year to year. Newly developed grasslands were occasionally brought to total ruin by the black cutworm, Agrotis ipsilon HUFNAGEL, shortly after sprouting of grass. The tabacco cutworm, Spodoptera litura FABRICIUS, rarely injured white clover in the southern region. Among indigenous noctuids, Amphipoea ussuriensis PETERSEN, S. depravata BUTLER and Xestia c-nigrum LINNE caused local outbreaks, the former two feeding on orchardgrass and the last on white clover.
