If you see Japanese beetles in your corn fields it could mean poor pollination is imminent. The pest loves to snack on corn’s delicate silks—and if they clip them to ½” or less the crop might not pollinate.
Consider a foliar insecticide treatment during tasseling and silking if there are three or more beetles per ear, silks are clipped to ½” and pollination is less than 50% complete, according to Eileen Cullen, University of Wisconsin Extension entomologist.
“[If applying an insecticide] beetles must be on the outside of the ear, which is normally the case,” Cullen says “The main concern with Japanese beetle feeding is to protect silks for pollination.”