Farmers can attest to the fact that not all caterpillars turn into beautiful butterflies. Some, like the voracious western bean cutworm, Striacosta albicosta, can clip yields in a heavily-infested cornfield by up to 40%.
Such yield losses in corn are a relatively new phenomenon. Historically, the western bean cutworm was a threat primarily to dry bean crops in states such as Colorado and Nebraska. Today, though, the western bean cutworm has travelled as far east as Pennsylvania.
“This summer we’ve seen significant populations in states including Michigan, Ohio and Pennsylvania,” says Missy Bauer, Farm Journal Associate Field Agronomist.
Bauer notes that the pest currently is in the larval stage, one of the five growth stages it experiences during its life cycle, and is actively chewing through ear husks to feed on corn kernels.
“They burrow into the side of the husks to feed on the ear,” she says, adding: “An infestation level of roughly one cutworm per ear results a yield loss of three or four bushels per acre.”
While corn yield loss from western bean cutworm feeding damage can be significant, Bauer points out it also provides an entry point for other yield robbers such as ear diseases, molds and fungus.
In the following video, Bauer shares some of the visual signs farmers need to look for as they scout field corn for the western bean cutworm during late August.
Can’t tell a bean cutworm from a black cutworm? Check out this link: