By Erin Hodgson
Stalk borer can be a reoccurring pest along the edge rows of corn adjacent to perennial grass borders, waterways, or terraces. The caterpillars move from grasses to corn when the stalk gets too small. Like all insects, they develop based on accumulating temperatures and right now, you could expect to see caterpillars moving throughout the southern half of Iowa.
There is a limited time to make a rescue treatment for stalk borer. Once they find a corn plant to infest, foliar insecticides are not effective. If you have experienced stand loss due to this caterpillar, scout now to make a treatment decision.
Source : iastate.edu