Several kinds of surface-feeding caterpillars are known as cutworms. Their name reflects their feeding habit, which is to chew plant stalks until they are cut through. They feed on many garden plants, and are especially fond of seedlings. Cutworms emerge at night, curling themselves around plant stalks to feed. Cutworms hide during the day, usually an inch or so below ground and near the scene of the crime.
There are three types of cutworms, each characterized the site of feeding: on plant roots; on seedlings at ground level; on buds above ground level. Adult cutworms are dark-colored, night-flying moths.
If your garden has been affected by cutworms in the past, take preventive measures. Apply beneficial nematodes to soil just prior to planting. A protective collar of cardboard circling each seedling and extending 2 inches below and above ground is an effective barrier. A band of diatomaceous earth around seedlings may deter egg-laying adults.
Cutworms are also vulnerable to predatory insects, including ground beetles and soldier beetles.
Photography by Whitney Cranshaw, Colorado State University, Bugwood.org