Most likely you have seen some darkly colored moths flying around farms, homes, and yards, especially to lights at night. They pop up from lawns during mowing and from both corn and (especially) soybean fields during harvest. These moths are actually mottled grayish-black with some dark brown mixed in. When at rest they have the triangular shape of a fighter jet. These are likely the adult green cloverworm (Noctuidae: Hypena scabra).
The slender green caterpillars feed on soybean foliage, as well as alfalfa, clover, and other leguminous plants – and there are a lot of those plants around the Indiana countryside. They can be found in every soybean field, every year, but are not considered a pest since they don’t do enough defoliation to cause yield loss. The caterpillars will rapidly arch their back and “freak out” when disturbed.
These insects are affected by a wide range of natural enemies. Normally, fungal pathogens, as well as insect parasites and predators, keep green cloverworm populations at relatively low levels in soybeans and we don’t notice the moths much. But every so often (roughly once every 5-7 years), we have a “big year” and an outbreak of the moths is noticed. This is one of those years; for unknown reasons, those natural controls were not as effective this year and allowed cloverworms to increase in number. The result is lots (and lots) of the adult moths flying around lights and residences.
These moths are a nuisance but will not harm anything. They will pass the winter in leaf litter and/or other sheltered areas and next spring the survivors will emerge and begin egg laying.
Close-up of green cloverworm moths on a window screen, showing variation in color.
Green cloverworm caterpillar on soybean leaf.
Green cloverworm larva parasitized by a wasp.
