How to Kill Cutworms in the Lawn

What Are Cutworms?

Cutworms are moth larvae that hide in the thatch layer of the lawn during the day, then come out at night to feed, chewing off grass blades close to the ground. The worms are 1½ to 2 inches long, with fat brown, gray, or black bodies; some are spotted or striped. Cutworms leave 1- to 2-inch-wide spots of brown grass with the blades chewed evenly along the edges or eaten off at soil level. You may see them curled up in the thatch if you peel back a section of damaged turf. Thankfully, because they are surface feeders, they are relatively easy to control.

Identifying Cutworms in Your Lawn

A large number of birds scratching and pecking at your lawn can indicate a sizable cutworm population in the grass. Although they are primarily a problem in early and late summer, cutworms can cause harm to lawns throughout the growing season. Once they are established in spring, several generations can hatch in one season and damage the lawn before they die out in the fall. Cutworm adults are dark moths with bands or stripes on their forewings. They are often seen fluttering around lights in the summertime.

Killing Cutworms

How to Find Cutworms 

Before you can kill cutworms, you have to find them. Pour soapy water on the damaged area of the lawn and wait about 10 minutes. If cutworms are present, they should start to emerge from the thatch layer, confirming your suspicions.

Treat Cutworms With Insect Killers 

Cutworm damage to mature, properly maintained lawns is usually not severe, but they can damage newly seeded lawns to such an extent that you have to reseed. If you see cutworm damage in your lawn, apply a control product in the evening, when they are most active. You can control cutworms with Scotts® GrubEx®1, or you can control cutworms and feed your lawn at the same time with Scotts® Turf Builder® SummerGuard® Lawn Food with Insect Control.

Prevention & Maintenance

Make Plant Collars

If you have a problem with cutworms in your garden beds, you can protect plant stems by creating small cardboard collars for each individual stem. These will protect your plants, but can be time consuming to make.

Control Thatch

Because cutworms hide in the thatch layer during the day, controlling thatch can help prevent cutworm infestations. Maintaining your lawn with regular feeding, proper watering and mowing, and periodic dethatching will help keep thatch from building up and providing a home for cutworms.

Keep a Well-Fed Lawn

Proper lawn care is the best medicine when it comes to cutworm prevention. When your lawn is stressed, thin, and undernourished, it has a higher chance of being taken over by weeds and pests. Regular feedings (every 6 to 8 weeks) during the growing season with Scotts® Turf Builder® Lawn Food will help your lawn stay thick and lush, making it less welcoming to weeds and pests.