How to Manage Pests

The UC Guide to Healthy Lawns

Cutworms and armyworms — Agrotis spp., Peridroma saucia, and Mythimna (= Pseudaletia) unipuncta

Granulate cutworm adult

Granulate cutwom larva

Variegated cutworm larva

Black cutworm larva

Parasitized armyworms

Click on images to enlarge.


Adults are dull brown or grayish, relatively large, up to 1-1/2 inches (3.8 cm) long, night-active moths. Larvae are caterpillars that are up to 2 inches (5 cm) long at maturity and often curl up and lie still when disturbed. The large size and behavior of larvae distinguish them from lawn moth caterpillars.


All turfgrass species


Cutworm and armyworm larvae chew and cut leaves around the crown. Damage begins in small, irregular spots and spreads to patches extending many feet in width. Armyworms, especially, prefer moist areas.

Monitoring information

Cutworms and armyworms are active from early spring through the fall. Look for fat, dull gray, green, or brownish larvae up to 2 inches (5 cm) long with a drench test. Inspect outdoor lights around dawn for 1-1/4 inch (3.2 cm) brownish to gray moths.


Reduce thatch and eliminate soggy areas. Larvae have some natural enemies, such as braconid wasps and tachinid flies. If more than 5 larvae per square yard are present, you may need to treat. Beneficial nematodes or an application of Bacillus thuringiensis (Bt) may be effective against young caterpillars. Other safe products are available.

Life cycle

For more information on lawn insects, refer to:
Pest Notes: Lawn Insects

Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2017 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   Contact webmaster.