Cutworms: How To Destroy Noctuidae Caterpillars In Your Garden

Ed Wike
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Cutworms Overview

There's nothing like picking ripe blueberries, tomatoes, peppers, eggplants, and other vegetables from the garden. And doing this at the end of the summer is one of the usual indicators that fall is on the way. Cutworms are a few challenges that are connected to this usually enjoyable part of the year, and the ones that you'll learn how to conquer in this post. So let's get to it.

The larvae of these small grayish moth species are not picky eaters. And one of the more than 200 caterpillar species known as cutworms are notorious for eating tender vegetables and fruit plants. Want to know more?

Many baby birds thrived on milk. And so do cutworms. Since they can't fly, they rely on their camouflaging skills as well as some natural predator avoidance to keep them out of harm’s way.

Cutworms have natural predators, but they are not as mobile as they are. That's why they are often called noctuidae, which in Latin means non-wandering.

These serpent-like caterpillars use a similar strategy as their namesakes and when resting, they curl up and look like tiny worms. Their camouflage tricks also make them difficult to find.

Types of Cutworms

Cutworms are familiar pests in both vegetable and ornamental gardens and can be particularly destructive to seedlings. Noctuidae are a large family of moths primarily found in temperate regions. The larvae of some species make for particularly serious concerns.

Although some species are innocuous or even beneficial to commercial and domestic crops, many pose a significant threat to individuals and local communities. The larvae feed on the stems and leaves of plants, often causing severe damage and death to all parts of the plant.

There are a number of species of cutworm that can be found in both the new and old worlds, with many inhabiting the midwestern regions of the United States.

The Problem

Cutworms are moths with soft brown or grey bodies that feed on a variety of plants. There are many different species, and all of them are pests in the garden.

Cutworms affect the appearance and production of many of the vegetables and ornamental plants most important to home and commercial growers.

Life Cycle

The cutworm completes its life cycle in one year or less and spends the winter in the soil as an adult. Adult moths have wings just large enough to allow them to hover over the plants from which they will oviposit. Eggs are laid in the soil at the base of the plant, and the eggs hatch in a short period of time.

Life Cycle of Cutworms

For northern gardeners, cutworms can be a serious problem.

Prior to the emergence of seasonal cutworms, young plants are threatened by the fall army worm. This worm migrates north in the fall and tunnels through the ground to reach plant roots, which it then eats. Neither the adult nor the larval stage of the fall army worm feeds on plants.

Once the soil freezes in the fall, the worms retreat to the soil and lay eggs. The eggs remain dormant in the soil for up to four years before hatching. In the spring, the worms hatch, emerge from the ground and begin their destructive work by chewing away at leaves and stems.

After eating their fill, cutworms are transformed into the pupae stage and return to the ground to lay more eggs. The mother worm lays anywhere from one to eight eggs per square foot and the total number of eggs laid can number up to a million.

Common Habitats For Cutworms

Cutworms are prevalent mainly in the late spring and early summer, and you'll see them feeding on your plants at night. Many gardeners want to know how to avoid cutworms because their work on the garden often goes unnoticed until the damage is done.

Cutworm larvae are often light in color with dark, distinct spots. They have a band around their body that has six small bumps protruding from it. They have a small brown head and segmented body.

Cutworms are one of the most annoying pests for gardeners because they do their dirty work in the cool, dark night. Identifying these pests is the first step to knowing how to get rid of cutworms in your garden.

Unfortunately, the damage done by these pests is pretty difficult to fix if you don't notice until morning. Here are the primary habitats of cutworms.

What Do Cutworms Eat?

Cutworms are the caterpillars of the moth order Noctuidae. They are found throughout the US in the spring and fall.

Cutworms are mostly brown, but some are black or striped. Some odder varieties have spots.

Cutworms eat:

  • Plants at or near the surface of the soil
  • Natural fibers – often buried near the surface
  • Petroleum-based products – often found around landfills
  • Paper – most common around construction sites
  • How To Combat Cutworms

Cutworms are difficult to drown because their bodies are air-filled, and they are able to breathe through their skin.

An Acceptable Gardening Alternatives

Remove weeds.

Turn the soil to expose caterpillars.

Replace mulch with gravel or rocks.

Let plants grow tall by staking and wrapping.

By setting out water-filled jars or bottles with mothballs.

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How To Get Rid Of Cutworms

Adults are not the only offenders when it comes to this group of caterpillars. Even before the young worms have reached adulthood, they can be troublesome pests. Once they are ready, the worms become night feeders, making their presence known by cutting the stems of plants, usually at a 45-degree angle.

The young larvae of the noctuidae family are soft-bodied and very difficult to see during the day. If you notice your plants have been damaged during the night, you may have noctuidae cutworms on your hands. These are serious pests that can wreak havoc in your garden. What can you do to get rid of them and stop them from messing with your garden?

If you are free to move your plants around, then do. Cutworms are going to be more attracted to darker areas near your plant, so you want the plants out of the shade when possible.

They will also stick to the ground, so if there are other spots in your yard where the plants may grow better, then do it.

Plants grown in containers should be moved around often. In fact, you may have to do this every couple of days if you want to ensure that you are thwarting the caterpillars

Organic Cutworm Control

Although it's not necessary to destroy cutworms before they do serious harm, if you want to protect your plants, you can. Here's how to get rid of cutworms organically.

Cutworms are nature's weed-eaters and they do a great job of keeping your garden clear of weeds, by eating your vegetables. To stop cutworm damage, you first need to know what a cutworm is and what can be done to stop it.

A cutworm is a number of species of small, light colored noctuid moths which have smooth, soft bodies. They overwinter as eggs, hatching in early spring after cold weather ends. They are called cutworms because, just as they do with weeds, they cut (or chew) into green plants, using their teeth to chew through stems. They leave a characteristic cut at the bottom of the plant, usually a few inches below the soil line.

There are four types of cutworms that are prevalent in the United States. Most cutworms are gray, brown, or black, and can be identified by looking for a pair of distinctive, feathered projections at the back end of the body. The pupal stage is light brown and can be found in soil, in garden debris, or within the tunnels cut by the larvae.

Environmental Cutworm Control

Cutworms prefer moist, actively growing lawns. One of the best defenses against this pest is to reduce the amount of moisture in the soil. A well-draining soil has fewer problems with cutworms than a moist, moldering one will.

Another is to plant in patches. This ensures that the lawn is not a continuous, lush carpet. Cutworms sometimes travel for food. Because of this, planting in patches across the lawn rather than just in patches at the edges will help reduce the population of cutworms in your lawn.

Garlic oil is a natural pesticide that you can spray on your grass to kill cutworms. While this will not eliminate them from your lawn, spraying every few weeks will keep them under control. The spray will also help prevent other insect pests.

Food Spots

Cutworms are bad in the spring and early fall because those are the times the worms look for food. You can destroy their food supply in the garden with a garden cultivator.

The best way to cultivate is to pull the grass after you have sprayed the lawn.

This will kill the cutworms when you turn the soil over and expose them to the air.

Another beneficial trick for a garden cultivator is to put out a bowl or a shallow dish of water.

The larvae will crawl out of the soil to the water's edge where they will be killed by the sun.

Preventing Cutworms

Cutworms are the larvae of a few different types of moths found in North America. The larvae are one of the main reasons why so many vegetable and fruit plants are destroyed by hungry critters in the home garden.

Caterpillars burrow just below the surface of the soil, where they damage the plants’ roots. The stem is the cutworm’s preferred meal, but it will devour the root if no other food source is available. If you know what to look for, you can prevent cutworms from devouring your garden.

How to identify cutworm damage.

If a plant is wilting and dying in your garden, there’s a strong chance it was killed by a cutworm caterpillar. Look for footprints in the soil where a little creature was busy gnawing and then look for a straight line of destruction in the plants.

You can prevent cutworm damage in your garden by mulching.

Frequently Asked Questions

Steve Lucas, MSU Entomology.

Michigan State University Extension

Q. I wonder if you could identify this caterpillar that looks like pink worms coming out of the soil in my garden. I bought this property and I am just getting started.

A. Welcome to MSUE!, I am an entomologist with the Plant Pathology Department at MSU Extension. You have found the caterpillars of the night-flying moths Noctuidae genera Halyomorpha halys, Laphygma, Ophiusa, and Eryngium which are commonly referred to as the cutworm.

These moths fly at night which is one reason why they are such a problem. They lay their eggs in the soil during the day and the eggs hatch by the end of the week. The caterpillars emerge from the soil at night and feed on the newly sprouted plants or seedlings. It is usually very difficult to determine the extent of damage before it becomes severe. The first indication of cutworm damage is usually small, irregular holes in the leaf, but the other identifying characteristic of cutworm damage is the sudden wilting of the plant canopy. This happens as a result of the cutworm eating the stems or roots of the plant. Damage to the leaves will be evident in a day or two after wilting.

Q: What are the largest and smallest cutworms in the garden?

Adult moths are generally dark gray with dark banded wings. Many of the moths are darker around the wing tips. These moths lay their eggs singly on the soil surface.

Cutworms are often confused with army cutworms, which are caterpillars. Cutworm caterpillars are pale gray, cylindrical caterpillars with dark eyespots on their undersides. They are generally between 2-6 inches long.

There are about 40 species of cutworms in North America, making identification difficult. Keep in mind as well that cutworms feed at night. Most species of cutworms are less than 3/4" long and can be difficult to identify. The best way to identify cutworms is to examine plants when the larvae have been caught out in the open. Look for the bit of brown or greenish-gray skin that will match the body of the caterpillar.

Q: Cutworms in my compost pile – is that bad?

It is rare that a problem with cutworms in a compost pile is likely to be a problem for the finished compost that is produced. So, if you have the occasional cutworm crawling around in your bin, you can rest easy. Should the cutworms be present in a large enough number that they may interfere with the decomposting process, you can choose to deflect them by adding some equipment to your composting location. Cutworms like to burrow into the ground to spend the day. You can prevent the cutworms from emerging by closing off any holes in your compost bin. You can line the bin with hardware cloth or mesh, or add a lid to keep the cutworms trapped. If you choose to add a lid, make sure that your lid has a vent to allow the moisture to escape.