In 2021, a farmer went to bed one night thinking he had plenty of pasture. Next time he went by that field, he couldn’t believe it. All that was left were plant skeletons. Fall armyworm doesn’t strike every year or everywhere, but when it does, it can be devastating.

That’s just one reason why entomologists recommend scouting your crops until the end of the growing season. Here are some pests that may or may not ever show up in your area. In case they do, know how to identify them.

Fall armyworm. “The spike in fall armyworm numbers continued over the past week in a number of counties in Ohio,” writes Amy Raudenbush, an associate entomologist at Ohio State University and lead author for reports in the OSU C.O.R.N. weekly newsletter. “Growers with corn, sorghum, small grains, pasture grasses and forage crops should remain vigilant in scouting for the presence of FAW egg masses and larvae.”

High moth numbers in traps don’t mean a fall armyworm outbreak will occur, but it is a signal to scout carefully.

Fall armyworms are much easier to kill when they are smaller, and feeding accelerates rapidly as they grow, entomologists note. Look for egg masses glued not only to vegetation but also to structures like fence posts. Egg masses have a fluffy-looking cover. When the cover is peeled back, eggs are pearly and tan when new, and turn darker as they approach egg hatch. 

Fall armyworm caterpillars vary in color, from greenish to tan to dark brown with stripes along the body. A good identifier is an inverted white Y shape behind the head. Another species, true armyworm, feeds at night, but fall armyworm will feed during the day.

Corn earworm. OSU entomologists also trap corn earworm moths. According to the late August C.O.R.N. newsletter, moth counts are low so far this year.

Based on descriptions in the Purdue University Corn and Soybean Field Guide, corn earworm larvae can be green, pink or tan to dark brown with alternating light and dark stripes. Look for a double, mid-dorsal dark line running the length of the body.

Western bean cutworm. This insect usually doesn’t work alone. Entomologists note that it’s common to find several in one ear. By harvest, ears are usually damaged by secondary disease infections.

According to the Purdue guide, look for two distinct dark triangles behind the orange-colored head. This pest tends to show up more in sandy fields. GMO traits help with control.

DOUBLE WHAMMY: These ears were first attacked by western bean cutworm larvae. Then, secondary disease ear mold fungi invaded through open feeding wounds. (Tom J. Bechman)

Sap beetles. If you find feeding, you also likely will find little black bugs in the ear — either a variety of species falling under the category of sap beetles, or picnic beetles, reports John Obermeyer, Purdue Extension entomologist.

“Their presence is in response to previous damage to kernels, which includes insect and/or bird feeding, and hail,” write Obermeyer and Christian Krupke, a Purdue Extension entomologist, in the Aug. 8 issue of the Purdue Pest & Crop Newsletter. “These small, opportunistic insects are feeding on decaying kernels and subsequent molds, not directly damaging the crop. They are simply fulfilling their niche in the cycle of life. ‘Clean up on Aisle 3.’”