REED CITY, Mich. — Winter cutworms are destroying fields, yards and gardens across northern Michigan.

Unlike most cutworms that feed on field crops and garden plants in the spring, this species is unique because it feeds primarily in the fall. It can even be found crawling around on the snow in early winter, according to Jerry Lindquist, Michigan State University Osceola County extension director.

The winter cutworm is native to Europe and was found first in Nova Scotia in 1979. The hairless worm-like larvae hatch in late summer and start feeding.

“Many farms on warm, sunny days have witnessed thousands of cutworms feeding in fields,” Lindquist said. “Once they strip the field of green vegetative material, they have a habit of moving en masse all in the same direction to the next field.

“This crawling mass of larvae, when detected in the fall, can cause great concerns for humans. Even non-farmers and gardeners may experience their impact, as reports of some of the larvae moving from the lawns to inside the household have been reported.”

The pest has been found in 12 northern Michigan counties, spanning from Alpena to St. Clair counties, with larger populations in the northwestern side of the Lower Peninsula. Lindquist said the larvae have shown a feeding preference this fall for alfalfa, clover, grass, rye and wheat, but also have been known to feed on squash, cabbage, carrots, lettuce, potatoes, strawberries, tomatoes, sugar beets and Swiss chard.

“We believe this year the feeding damage this late in the growing season does not warrant insecticidal control,” Lindquist said. “But, farmers will have to watch their fields of alfalfa, wheat, oats and corn closely next year to prevent possible damage.”

MSU Field Crops Entomologist Chris DiFonzo said cutworms are quite a common pest in Michigan gardens. However, she has not heard a report of this type of larval damage before, and is concerned about potential winter damage in weakened crops. “This may be one of the first reports ever of crop damage,” she said. “They gather together and eat and make this kind of defoliation front. When you lose all that plant material, there’s nothing to hold snow. You don’t want the alfalfa crowns to have no cover and have damage due to freezing.”

DiFonzo said it’s too soon to estimate long-term impacts of the infestation.

“They are very cold-tolerant,” she said. “This will remain, presumably, over the winter. But, I’m not sure what will happen in the spring. We are encouraging farmers to look at their fields again in March for additional damage.”

Lindquist said larvae will emerge in April, begin feeding and pupate into a moth in May or June and then lay eggs, starting the cycle again.

“Soil tillage seems to diminish the population, but all it will take is an untilled field within crawling distance, and the crop in the tilled field could be at risk,” Lindquist said.

If more feeding activity is found, farmers can apply a pesticide for control.

“Control is fairly easy with most insecticides labeled for cutworms, in the appropriate crops, providing effective control,” Lindquist said. “Because they are new, we will have to watch our fields carefully next spring and see how extensive the damage is. “Most of this fall damage thus far has not killed the alfalfa nor wheat, just weakened it so it may not produce as well next year.