How to Get Rid of Cutworms Fast Before They Damage Your Garden This Summer

• Cutworm is a generic term referring to the caterpillar of various moth species that attack herbaceous plants.
• Cutworms appear in swarms to eat through tender stems at the soil line, destroying agricultural crops and gardens.
• Cutworm control measures include preventative tasks, garden monitoring, physical barriers, and manual removal.

While moths are usually innocuous in the garden, their caterpillars can cause lots of problems. These caterpillars—collectively referred to as cutworms—can cut down garden seedlings seemingly overnight.

Since moths can go through three generations in a year, you should learn how to identify cutworms and the damage they cause. Here are ways to reduce the number of eggs that will hatch and how to get rid of cutworms.

How to Identify Cutworms and Their Damage

While there are color variations, most cutworm species in U.S. gardens look very similar. The caterpillars are smooth and about two inches long. They can be dull or glossy, brown, tan, black, pink, gray, or green, and solid, spotted, or striped. There are climbing cutworms that move up the stem of plants and surface cutworms that remain at soil level.

Cutworm damage is most severe in spring when plants are small or have tender tissue. Climbing cutworms crawl up stems of trees, shrubs, vines, and vegetable plants to cut holes in the leaves or eat buds and fruit.

One identifying quality of surface cutworms is that they typically curl into a tight ‘C’ shape when disturbed. This is also how surface cutworms feed: They curl their bodies around the stem and begin to eat. The feeding causes the plant to appear cut off just above the soil surface.

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How to Get Rid of Cutworms

There are various methods to get rid of cutworms, and each has its own advantages. Depending on what you need, here are six option that might work for your garden.

Manual Removal

Inspect the garden at dusk or very early in the morning daily when the cutworms are most active. When cutworms are discovered on plants or the ground, physically remove them while wearing gloves and crush or drop the insects into a bucket of soapy water.

Aluminum Foil Collars

You can create a physical barrier to prevent surface and climbing cutworms from attacking plants. Cut a strip of aluminum foil about 12 inches wide and fold it in half so it is 6 inches tall. Cut into shorter lengths so that the collar isn’t too large. Push one end of the collar 3 inches into the soil, and the other end extends 3 inches above the ground. Leave it in place for several weeks until the cutworms move into their next stage of life.

Cardboard Collars

Cut heavy duty cardboard (mailing tubes) into rings with a side slit to fit around plants. Position like aluminum foil collars with several inches of the collar below and above the soil.

Diatomaceous Earth

Diatomaceous earth is a gritty, sharp powder that damages the cutworm as it crosses and causes it to dehydrate and die. Sprinkle it liberally in a circle around tender plants.

Dish Soap and Water Spray

There is anecdotal evidence that a spray bottle filled with water and about 1 teaspoon of dishwashing liquid will kill cutworms. This will only work if the solution is sprayed directly onto the cutworm.

Commercial Pesticides

Synthetic pyrethroid insecticides such as deltamethrin, cyfluthrin, bifenthrin, permethrin, and lambda-cyhalothrin will work very well to reduce damage from cutworms. The organic pesticide Bt (Bacillus thuringiensis) or beneficial nematodes will also work.

Follow label directions carefully to prevent harm to beneficial insects, pets, and humans. Between midnight and dawn is often the most effective time to make an application.

How to Keep Cutworms Away

The best way to prevent cutworm damage is to take early control measures in the garden to reduce the number of moth eggs.

• Clean up residue and weeds around your garden to make areas less attractive for egg laying.
• Till the garden soil in the fall to destroy eggs, larvae, or pupae in the soil.
• Leave a three to four-foot area of bare soil around valuable plantings to make it more difficult for cutworms to crawl across.
• Keep weeds under control because they can act as a host for young cutworm larvae.
• Use compost instead of green manure, as manure may encourage egg-laying.
• Maintain a three to four-foot buffer of dry soil along the edge of the garden to make it unattractive to cutworms.