Cutworms can be a gardener’s nightmare, causing damage to a variety of plants and ruining all the hard work put into cultivating a beautiful garden. These pesky critters are the larvae of various species of night-flying moths, including the bronzed cutworm, variegated cutworm, black cutworm, dingy cutworm, glassy cutworm, and army cutworm. They are known to feed on plant stems, leaves, and even the roots, often causing severe damage or even killing young plants.
Getting rid of cutworms requires a combination of vigilance, preventative measures, and targeted interventions. In this article, we will discuss some practical and effective strategies for controlling these destructive pests while protecting your precious plants. Stay tuned to learn how to send cutworms packing and restore your garden’s health and beauty.
Types of Cutworms
There are various species of cutworms, with some common ones being:
- Bronzed cutworm
- Variegated cutworm
- Black cutworm
- Dingy cutworm
- Glassy cutworm
- Army cutworm1
Their colors and markings vary from dingy white to tan, brown, and charcoal gray2.
Life Cycle of Cutworms
Cutworms progress through these key stages:
- Eggs: Adult moths lay eggs on foliage.
- Larvae: The larvae feed on stems and leaves of plants.
- Pupation: They become pupae as they mature.
- Adult: The adult moths emerge and proceed to lay eggs.
Cutworms typically overwinter as pupae, with additional moths migrating from the south during spring3.
Cutworm Damage on Plants
Cutworms cause damage and stress on plants in the following ways:
- Chewing stems and leaves at night4.
- Burrowing through the thatch or soil5.
- Severing plants to feed on wilted material5.
Damage may appear as circular spots of dead grass, finger-sized brown crescents, or ball marks on a golf green5.
Preventing and Controlling Cutworms
Cultural Control Methods
To prevent cutworm damage, you can take some simple steps in your garden:
- Remove weeds: Cutworms are attracted to weedy areas1. Clearing weeds provides fewer hiding places for these pests.
- Till the soil: Tilling your garden before planting can expose cutworms to predators and the elements2.
- Plant later in spring: Waiting until later in the season to transplant your seedlings can help you avoid the worst of cutworm infestations3.
Biological Control Methods
Introducing natural enemies of cutworms can help control their population:
- Birds: Encourage birds to visit your garden by providing birdhouses, birdbaths, and feeders4. Many birds, such as robins and starlings, eat cutworms.
- Trichogramma wasps: These tiny beneficial insects are known to parasitize cutworm eggs5. You can purchase them online or from garden stores.
- Nematodes: Beneficial nematodes can be applied to the soil to help control cutworm larvae6. These microscopic worms are harmless to plants and humans.
Chemical Control Methods
If you need to resort to chemical methods to manage cutworms, consider the following:
- Bacillus thuringiensis (Bt): Bt is a natural soil bacterium that is toxic to cutworms7. Apply Bt as a spray at the base of your plants during the evening when cutworms are active.
- Insecticides: Chemical insecticides can be used to control severe infestations. Be sure to follow the label instructions and use caution to protect beneficial insects.
Pros and Cons of Chemical Control Methods
|Effective in managing large infestations
|Can harm beneficial insects
|Quickly reduces cutworm population
|May require multiple applications
|Potential environmental impact
Remember, it’s essential to practice an integrated pest management approach to keep your garden healthy. By combining cultural, biological, and chemical control methods, you can effectively manage and prevent cutworm infestations.
Protecting Your Garden
Cutworms are the larval stage of various night-flying moths. Common species, like the variegated cutworm, can be identified by their soft, plump, and hairless appearance. Their 1-2 inch long caterpillars display colors that vary from dingy white to tan, brown, or charcoal gray1. These garden pests usually hide during the day, blending with dirt and debris, and become active at night, causing damage to young plants and seedlings2.
Plant Collars and Barriers
To prevent cutworm damage, install barriers around your young plants and seedlings. Some effective materials to create collars include:
- Aluminum foil
- Brown paper
Simply wrap the material snugly around the base of your plant, extending about 1-2 inches below the soil line and 2-4 inches above3. This barrier will stop cutworms from reaching your plants’ tender stems.
Natural Predators and Beneficial Insects
Introducing natural predators and beneficial insects to your garden can help control cutworm populations. Some options include:
- Nematodes: microscopic worms that attack and kill cutworms4
- Bacillus thuringiensis (Bt): a naturally occurring bacterium toxic to cutworms when ingested5
- Birds: attract birds by providing nesting sites and birdhouses. They will feast on cutworms.
|Targeted and effective; no harm to plants
|May require reapplication
|Effective against many caterpillar species
|Must reach all cutworms
|Natural and efficient predators
|May also eat beneficial insects
Diatomaceous Earth and Other Deterrents
Diatomaceous earth is a natural powder that can be used as a barrier around plants, effectively deterring cutworms from reaching them. When cutworms come into contact, the abrasive material damages their outer layer, causing dehydration and eventually death6. Spread a thin layer of diatomaceous earth around the base of your plants, reapplying after rainfall.
Other deterrents include:
- Interplanting strong-smelling flowers, like marigolds or lavender, to mask the scent of vulnerable plants
- Using cabbage leaves as bait and checking them daily for feeding cutworms
- Tilling your garden in the fall to expose cutworm pupae, reducing the population next spring
Home Remedies and Tips
Using Soapy Water
Soapy water is an effective, eco-friendly solution for getting rid of cutworms. To use this remedy:
- Mix a few drops of dish soap with water
- Spray the mixture on your plants
Soapy water can suffocate cutworms and decrease their population in your garden. However, this method may need to be repeated regularly for better results.
Coffee grounds work as a natural repellent for cutworms. To use this method:
- Collect used coffee grounds
- Sprinkle them around the base of your plants
Coffee grounds have the added benefit of being rich in nitrogen, which can help improve your soil’s fertility. However, be cautious not to overuse coffee grounds, as excess amounts can make the soil acidic.
Eggshells are another effective, eco-friendly option for controlling cutworms. Some benefits of using eggshells include:
- Deterring cutworms with their sharp edges
- Providing a source of calcium for plants
To use eggshells:
- Crush the eggshells into small pieces
- Scatter them around the base of your plants
Eggshells can create a barrier that cutworms are less likely to cross due to their sharp edges. Be sure to replace eggshells periodically as they break down and lose their effectiveness.
Here’s a quick comparison of the three methods:
|Needs to be repeated regularly
|Can make soil acidic in excess amounts
|Requires regular replacement and maintenance
By using these simple home remedies, you can protect your plants from cutworms without the need for chemical pesticides. Choose the method that best suits your garden’s needs, and remember to apply them regularly for best results.
Cutworms and Specific Plants
Dealing with Cutworms on Vegetables
Cutworms are known to attack a variety of vegetables, such as asparagus, beans, cabbage, carrots, celery, corn, lettuce, peas, peppers, potatoes, and tomatoes. Here are some ways to protect your vegetables:
- Keep a 3- or 4-foot strip of dry soil around the entire perimeter of the garden to make it unattractive to cutworms.
- Use physical barriers by placing collars around transplants to prevent cutworms from accessing the plants.
- Plant sunflowers as a trap crop around the perimeter, as cutworms prefer them. Hunt and kill cutworms daily.
Protecting Trees, Shrubs, and Vines
Cutworms can also feed on turfgrass and can occasionally damage trees, shrubs, and vines. To protect these plants:
- Regularly check roots and surrounding soil for cutworms and remove any found.
- Keep a clean garden, as cutworms prefer to lay eggs on decaying plants or compost.
Comparison Table: Protection Methods
|Dry Soil Perimeter
|Easy to set up
|Effective for transplants
|Requires daily monitoring
Overall, using a combination of these methods can help reduce cutworm infestation and minimize damage to your plants.
Identification and Signs of Infestation
Cutworms are the larvae of night-flying moths, with wingspans ranging from 1.5 to 3 inches. The larvae can grow up to 1-2 inches long. The coloration varies from dingy white to tan or darker tones such as brown, charcoal gray, or even black. Some common species like black cutworms can be identified by their unequally sized small, dark wart-like bumps on the upper edges of their body segments. For a quick physical comparison of cutworm species:
|Black, gray, or brown
|Tan or brown
|Brown with yellow or white stripes
|Dark brown or black
One sign of infestation is the presence of cutworm droppings. These can be found near the base of plants or around damaged areas, and are small, pellet-like, and dark green or black.
Cutworms usually hide during the day near plant stems or just beneath the soil surface. They come out at night to feed on foliage, plant collars, and young stems at ground level. Damage signs include:
- Clusters of droppings near plant stems or ground level.
- Plants with severed stems or chewed collars.
- Plant tops and foliage showing signs of feeding.
- Curled-up cutworms near damaged areas.
- Evidence of cutworm larvae moving up trees, shrubs, and vines to feed on buds and newly emerged leaves.
Prevention methods to avoid cutworm damage include:
- Tilling soil around plants to disturb larvae hiding places.
- Using barriers, such as collars or foil, around plant stems.
- Employing biological controls, like bacterium or beneficial nematodes.
- Introducing non-toxic baits, like cornmeal or sliced potatoes, to attract and kill cutworms.
- Removing potato tubers and green manure plants from the garden, as they can attract egg-laying moths.
Chemical pesticides should be considered as a last resort and utilized only when other methods have proved ineffective.
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – The Mystery of the Cutworm and the Chrysalis
Caterpillar munching on chrysalis
Location: Rancho Bernardo, CA
December 8, 2010 1:46 am
This site is awesome! Please help identify this caterpillar that has been feasting on my Anise Swallowtail chrysalis. I found him on 12-5-10 tunneling through this chrysalis and also found a few other empty shells. I live in San Diego, CA.
The caterpillar in your photo looks like a Cutworm, the caterpillar of a Dart Moth in the subfamily Noctuinae. The odd thing is that in neither of your photos is any actual eating occurring, and the tail end of the Cutworm appears attached to the Chrysalis. The Chrysalis also appears to have a hole indicating that it was parasitized by an Ichneumon. We will not be tagging this as a Food Chain image because the evidence does not indicate that the Cutworm fed on a living Chrysalis.
Thank you for the reply. I have a screened cage where I have about 15 swallowtail chrysalis. On Sunday I was cleaning out some plants when I noticed one chrysalis had a large hole in the side and it was empty. That is when I discovered this ‘cutworm’ hanging out of another chrysalis. When first found he was head first in the chrysalis with tail end hanging out. I removed the chrysalis and cutworm from the enclosure, placed in a tupperware and took some pictures. These first pictures showed the head inside the chrysalis and the tail end hanging out (it appeared to be eating). Withing an hour it backed out of the chrysalis but it kept grabbing at the chrysalis and moving it around the tupperware container. Then it went back into the chrysalis and exited through the bottom of the chrysalis which are the pictures I posted. I thought those pictures provided a better view of the ‘cutworm’ since the previous pictures I took only showed the tail end. I found the whole situation odd since I had never seen a hole this large and I did not see any wasps or indication of anything else that would have caused this.
I do appreciate your feed back. Thank you so much.
Thanks for the additional information Cindy. Perhaps one of our readers will be able to provide some insight into this unusual phenomenon.
Karl solved the mystery (at least to our liking)
The Mystery of the Cutworm and the Chrysalis – December 8, 2010
Hi Daniel and Cindy:
It is a Noctuid moth but the subfamily is Heliothinae. It looks like a Corn Earworm (also Cotton Bollworm and several other common names), Helicoverpa (=heliothis) zea. The caterpillars come in a wide variety of colors and they change color as they progress through their moults. They are considered a very serious pest on many agricultural crops, although they apparently favour corn. The question of course is, was he caught in the act or was he an innocent bystander? Well, if any caterpillar could commit such a crime, this would probably be it. These are aggressive little guys with predatory tendencies and a reputation for cannibalism. According to one report (Chilcutt 2006), cannibalism may in fact be the most important mortality factor for H. zea. Predation on other species also has been reported, but appears less common. If he didn’t do it, perhaps he was just sniffing around for leftovers. Regards. Karl
This is like an Agatha Christie episode of the insect world. Cannibalism in Caterpillars, and then out and out predation of a harmless slumbering chrysalis. After Cindy’s last email, I had already reconsidered the reluctance to tag this posting as “Food Chain“.
Letter 2 – The Laugher
My son found this caterpillar in the garden of our Northern Virginia home. Could you tell us what it is? We’ve tried looking it up with no luck.
This caterpillar is known as The Laugher, Charadra deridens. It feeds on the leaves of beeches, birches, elms, oaks, and other broadleaf trees.
Letter 3 – Turbulent Phosphila Caterpillar
Black and White Horizontal Striped Caterpillar
Tue, Nov 4, 2008 at 7:34 PM
My daughter and I found this caterpillar that we cannot find a match for anywhere on-line. I sifted through many of your pics of caterpillars and typed in search information for: black and white horizontal striped caterpillar. Nothing came up. The closest identification we could come up with was catalpa caterpillar but ours does not have a tail thing that sticks up like the photos of catalpas and it seems catalpas are more greenish than white. And there are no catalpa trees in the vicinity that it was found. It was found this month: November on an old gravel logging road that’s wooded on both sides, mostly pine, gum and oak trees.
Laurie and Lindsey
SW Arkansas (Arklatex)
Hi Laurie and Lindsey,
Sorry to have taken so long to reply since we recognized your caterpillar as something we had identified in the past, but between work obligations and the slowness of our 5 year old computer, it has taken us longer than usual to identify an image we wanted to post. We found two examples of your caterpillar in our archives dating from September 2005. Back then it also took us days to properly identify the Turbulent Phosphila, Phosphila turbulenta, which ranges in the Eastern U.S. and Canada and feeds on Greenbriar.
Letter 4 – Unidentified Caterpillar is Galgula partita
Location: Orange, California
February 7, 2011 3:15 am
I was outside today gardening and hanging out with my cats when I saw this caterpillar in the garden. At first I thought nothing of it because I rarely see caterpillars in my garden on grass growing between bricks and I didn’t think it was one because of the shape and where it was. (I’m not sure where it came from because we had been cutting, trimming and removing plants from our garden.) But I went back and to my surprise it had a fat head/neck. And on further inspection It was black with yellow stripes. And small little yellow spots. It kind of reminded me of an army worm but I don’t think it is because of the body/head shape and plus it was so small. I took it to my butterfly bush and hope to see if I can find it tomorrow.
We tried browsing through the Cutworms in the very large subfamily Noctuinae on BugGuide to no avail. We are so amused by your photos that we are posting them in the hope that one of our readers may eventually supply us with a species identification. Your Caterpillar makes an interesting fashion accessory.
June 5, 2011 2:08 am
Hi, I sent these pics to you in feburary and was wondering if you got any information on them? I’m still interested in knowing what kind of caterpillar this is. Thank you..
We did not have any luck in our initial attempt to identify this caterpillar, and unfortunately, none of our readers ever supplied us with an identification. Sorry to disappoint you. Sometimes identifications eventually happen months or years after the initial posting.
Update: February 16, 2014
We just received a comment indicating that this looks like the caterpillar of the Wedgeling Moth, Galgula partita, and upon viewing examples on BugGuide, we concur that it looks like a match. According to BugGuide: “The larvae feed on Oxalis sp. (wood sorrel).”
Letter 5 – Unknown Cutworm from Namibia
Subject: Caterpillar ?
Location: Packaging says Namibia
December 17, 2016 9:44 am
I hope that you can help me, for a bit of fun I’m going to enter the attached image in a nature photographic competition the guy responsible for entries at our Photographic Society is a bit harsh I just want to test him. Unfortunately we have to provide the name also in Latin.
Can you help
These are grapes that we bought, hopefully the grapes and packaging will give an indication of size
This sure looks like the larva of an Owlet Moth in the family Noctuidae, and it would be fair to call it a Cutworm, but alas, we are not going to be able to provide you with the desired species or genus name.
Letter 6 – Unknown Moth Caterpillar
Subject: A Mystery Caterpillar
Location: Circle B Bar Reserve, FL
October 8, 2015 4:30 pm
Hello, and thank you for ID-ing that ground spider!
So today I have a caterpillar found in 10/20/13.
Signature: Cicada lover
Dear Cicada Lover,
This request has been on our back burner because we did some research but we were not successful in determining an identification. This caterpillar really reminds us of a Hooded Owlet Moth Caterpillar from the genus Cucullia, but we could not find any matching images on BugGuide. We still believe it is a member of the Owlet Moth family Noctuidae. Perhaps one of our readers will have more luck with an identification.