CUTWORM: attacks young transplants and newly emerged seedlings.
Across the United States there are numerous varieties of the cutworms. The most common are the black (Agrotis ipsilon), bronzed (Nephelodes minians), dingy (Feltia jaculifera), glassy (Apamea devastator), granulate (Feltia subterranea), spotted (Xestia dolosa), army (Euxoa auxiliaris), winter (Noctua pronuba), red-backed (Euxoa ochrogaster), cutbacked (Agrotis gladiaria) and variegated (Peridroma saucia) cutworms. These are moths in the family Noctuidae.
There is not a single garden that is safe from these little critters if you are not actively managing your home garden environment. The presence of pests and diseases in your garden is often a direct result of certain conditions that can be controlled or improved upon by the gardener. No pest or disease is found in your garden without a cause, and cutworms are no exception to this rule. These nocturnal larvae, which are the immature stage of various moth species, thrive in environments that are conducive to their development and survival.
Understanding the underlying causes of pest presence, particularly cutworms, is essential for any gardener aiming to maintain a thriving and healthy garden. By actively managing your garden environment and fostering a balanced ecosystem, you can significantly reduce the risk of cutworm infestations and ensure the vitality of your plants.
What are Cutworms?
Moths start mating and laying eggs as early as spring, like the black cutworm, and continue through late summer or fall, like the dingy, glassy, variegated and bronzed cutworms. While adult moths do not damage plants, they will feed at dusk by sucking nectar from flowers and are often attracted to lights at night.
A lot of cutworms start getting active early in the spring when there aren’t many plants around, and moths will lay their eggs on any green plants, even weeds and cover crops. Female moths can lay a ton of eggs, either one by one or in small bunches which are usually laid on or near low plant and plant flowers
Cutworms got their name because they munch through the stems of young plants, basically cutting them down to the ground. You might have just one type of cutworm in your garden, or maybe a few different ones. Where we live, the common cutworms in Georgia are the black (Agrotis ipsilon (Ashmed)), granulate (Agrotis subterranea (Fabricius)), and variegated cutworms (Peridroma saucia (Hubner)).
Most cutworm species look pretty much alike. Their distinguishing characteristics include:
The caterpillars are mostly smooth with a few hairs and can get up to about two inches long.
If they get disturbed, they often curl up into a tight 'C' shape.
They come in lots of colors, like brown, tan, pink, green, gray, and black. Some are just one color, while others have spots or stripes.
Some larvae look kind of dull, and others are shiny.
The young larvae munch on leaves or little roots until they’re about half an inch long, then they move on to seedling stems, cutting or burrowing through them.
Cutworms typically emerge from their underground hiding spots at dusk, where they feed on the tender stems of young plants, cutting them down at the soil level. This destructive feeding habit can lead to significant damage, especially in the early stages of plant growth. The likelihood of cutworm infestations increases in gardens that have not been properly maintained, particularly if there are patches of bare soil, excessive debris, or an overabundance of weeds that can provide shelter and food sources for these pests.
How many cutworms you get depends on the weather, especially the rain and you might have up to three generations each year. Often with overlapping generations.
Host Plants
What do cutworms love the most? The answer: pretty much anything they can munch on. They hang around a huge variety of plants and flowers.
Some of the plants they like include, but are not limited to:
asparagus
beans
cabbage and other crucifers
carrots
celery
corn
lettuce
peas
peppers
potatoes
tomatoes
Damaged Caused by Cutworms
Cutworms wrap themselves around plant stems and munch away, which can chop the plant off right at the soil line. The number of cutworms can really change from year to year. When there are a lot of them, they can cause major damage.
Cutworms are nighttime feeders, hanging out in plant debris or soil during the day, so you might see plants that look damaged or cut but not spot the critters themselves. Black, bronzed, and army cutworms are pretty aggressive, attacking and cutting down new plants every night.
The variegated cutworm is a bit more adventurous; it climbs up trees, shrubs, vines, and garden plants to snack on leaves, buds, and fruit. Some types, like glassy cutworms, stay underground and go after the roots and other parts of the plant below the surface.
New transplants or young plants are more vulnerable because their stems are smaller and softer. The worst damage happens early in the season when plants are small and tender.
Cutworms are busy all summer but usually stop being a problem after spring.
Management of Cutworms
It is always the best practice to take a look at your plants in the morning when any damage is fresh and easier to spot. Keep an eye out for plants that are cut off close to the ground or those that are wilting (this happens when cutworms munch on the stems but don't completely chop the plant). A sure sign that cutworms are snacking is if you notice droppings on the ground.
You can also look at your garden in the late afternoon and evening since that's when cutworms are more active. To see if they're around, just run your hand over the soil, checking any clumps or potential hiding spots within a foot of the damage. If they're there, they'll curl up into a "C" when you touch them. For types like black cutworm that hide in the soil, you might spot a noticeable hole near damaged or cut plants. It is also much easier to deal with cutworms when they're still small.
For some plants, like tomatoes, peppers, and celery, you might find cutworms climbing up stems and munching on leaves and fruit later in the season.
Biological Controls
There many things you can do from natural predators to sprays that you can use to control cutworms in your garden. In our garden, there two main biological controls we have implemented to control cutworms in our garden:
Spraying plants with Bacillus thuringiensis kurstaki (btk) *. We only do this if there is a serious problem of cutworms. In our second year of growing tomatoes we had a cutworm issue. They would crawl up and all over our tomato plants, eating the fruit and leaves. We started with a mechanical approach by trying to pick them off and putting them in soapy water. It was so bad, that the fastest way to get it under control was to use Bacillus thuringiensis kurstaki. Thankfully we have only ever needed to this once and we only use it if it is necessary not as preventative message. Our preferred method of prevention is stronger plants and soil.
One good thing about using Btk is that it’s safe for other animals and bugs after it’s sprayed or eaten by the target pests. Birds and other predators can munch on the infected pests without worrying about toxic chemicals. When a cutworm eats it, the alkaline environment in its gut makes the Btk bacterium release a crystal protein, an endotoxin, which paralyzes the cutworm's digestive system. The cutworm stops eating and die soon after that.
Sc (Steinernema carpocapsae) Beneficial Nematodes are live microscopic organisms (non-segmented round worms) that occur naturally in soil all throughout the world. These beneficial nematodes are parasitic to insect pests that typically have a developing (larval or pupal) stage of life in the soil. They have been known to parasitize above ground stages of adults, nymphs and larvae. They will not harm mammals, aquatic life, birds, reptiles or amphibians. After being applied to the soil, the nematodes locate pests and enter through various body openings or directly through the body wall. Once inside, the nematodes produce bacteria that is injected into the pest's blood.
We have used these in our garden for many years and have found that they are very effective in reducing pest populations. Quite frankly, this is our go to method of pest control. We not only spray the ground, but we also spray all over the plants too. As a side note, this has been really effective for us with keeping at bay vine borers! We have sprayed this also a preventative measure long before we see any damage that might be caused bug or insect. We do this because often the bug or insects starts out their life in the ground. And if an egg as been deposited on a leaf, the nematodes will take care of that too.
Mechanical Controls
Hand picking and squishing is very effective. If you see a cutworm on the ground you can step on it and squish it too. I mean who doesn't love handling cutworms and squishing them!
If you are not inclined to want to squish them, hand picking and drop them in soapy water is very effective also.
Place collars around transplants. Push them into the ground. Be careful to not push the collars into the root zone as you do not want to damage the roots.
Cultural Controls
When your plants have finished their life cycle, remove them from your garden. Helps limit the amount of places eggs can be laid.
Weed management is critical. Although if you have taken the time to ensure you are developing good healthy soil, so that the soil food web is in place, then weeds will be very limited if not gone. A weedless garden is the ideal for all us gardeners! Let's work smarter not harder.
Keeping the soil food web healthy and robust is our preferred cultural method of dealing all pests include cutworms. We believe this to be a fundamental principle that serves as the foundation for successful plant growth and soil cultivation. Healthy soil, rich in organic matter, nutrients, and beneficial microorganisms, all contribute to the overall vitality of the plants that grow in it. When the soil is well-aerated and has good drainage, it allows roots to penetrate deeply, accessing water and nutrients more effectively. Since we have been dong this we have noticed the pressure from pests including cutworms has reduced considerably or we have not found them in our garden at all.
Harnessing Beneficial Microorganisms for Cutworm-Resistant Gardens
Microorganisms like bacteria and fungi form a protective barrier around plant roots, creating a microscopic layer that combats harmful pests such as cutworms while strengthening the plants' natural defenses. Prioritizing soil health is crucial for cultivating a resilient garden that can resist pest challenges. Healthy soil is rich in organic matter and teeming with beneficial microorganisms, which boost plant vitality. By enhancing your soil with beneficial biology, which includes benefical nematodes, you support nature's defense force in protecting your plants and reducing their vulnerability to pest damage.
Ultimately, by prioritizing soil health and fostering a diverse ecosystem filled with natural predators, and using a combination of other control mechanisms as necessary, you can create an environment where cutworms are no longer a problem pest you need to deal with.
Happy Gardening!
* CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Be sure that the plant you wish to treat is listed on the label of the pesticide you intend to use. And observe the number of days between pesticide application and when you can harvest your crop. Remember, the label is the law.
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