Mixed populations of variegated cutworms and yellowstriped armyworms have been reported on alfalfa in southern Wisconsin.
“Intense” cutworm moth flights and egg laying were also recorded in the northern part of the state, says Bryan Jensen, University of Wisconsin Extension IPM program manager. “This damage is likely from migrating (cutworm) moths although some overwintering is likely,” he says.
The nocturnal variegated cutworm moths have 1½”-long, dark-brown forewings with mottled designs. Hind wings are lighter in color. Larvae are up to 2” long, vary from light to dark brown and curl up into balls when disturbed. Many but not all larvae have single rows of yellow dots on their backs. The climbing cutworms feed on foliage and usually don’t “cut” plants as do black cutworms, Jensen says.
Larvae of yellowstriped armyworms (pictured) can be up to 1¾” long and are usually grey to black in color. They have two distinct yellow stripes on each side of their bodies. These foliage feeders hunger for grasses and broadleaved field and vegetable crops.
“In the southern part of the state, we are very close to harvest and that should be your first control option, if feasible,” Jensen reminds growers. “Most of my concern would be protecting the regrowth. These larvae can survive harvest and would likely start feeding on newly formed crown buds or shoots.” They can survive by hiding under windrows.
If fields haven’t greened up, don’t assume the problem is worm feeding; lack of rain could be a cause this year. To find either type of worm, inspect the soil surface, under leaf litter and in soil cracks.