Larvae feed on roots and foliage starting in late spring, but damage increases as the larvae gain in size and appetite. In dry summers, cutworms can crawl up plants and chew holes in the foliage that look like damage done by slugs.
Cutworm collars which are 5-7cms across, pressed 2.5cm into the soil around vulnerable plants, are usually effective. They can be made of cardboard, metal cans, or plastic drink cups cut into rounds. Gently digging or hoeing around the base of susceptible plants will often expose cutworm larvae to insectivorous birds such as robins.
As soon as you suspect cutworm damage, use a fork and flashlight to find the culprit at night; one individual cutworm can do significant damage. Check at hourly intervals at night and you can catch them as they show themselves.
Frequent shallow cultivation can expose and kill cutworms. Attract insect-eating birds by providing convenient perches nearby.