By Matt Gibson
There are over 20,000 different species of cutworms. Among the most common of the cutworm varieties are armyworms, surface feeders who terrorize gardens, munching plants down until just the skeleton of the leaves remain and gorging themselves on the fruits and vegetables that you’ve worked so hard to cultivate.
They hide on the undersides of leaves during the daytime and come out at night to destroy your crops.
Important Armyworm / Cutworm Facts for Gardeners
|Common Names||Armyworms, Cutworms, Army Cutworms|
|Scientific Name||Spodoptera spp.|
|Type of Pest||Insect (Moth), caterpillar|
|Affected Plants||Vegetables, grasses, grains (e.g., corn, wheat, rice)|
|Damage Symptoms||Irregular holes in leaves, skeletonized foliage, damaged fruits, defoliation|
|Life Cycle||Egg, larva, pupa, adult|
|Feeding Habits||Nocturnal feeding, prefer younger leaves|
|Peak Activity||Warm and wet weather|
|Prevention Measures||Crop rotation, regular monitoring, removal of weeds|
|Control Methods||Manual removal, natural predators (birds, beneficial insects), Bacillus thuringiensis, Spinosad, Neem, insecticides|
- Armyworms are actually the larval stage of moths in the family Noctuidae.
- They’re called armyworms because of their tendency to move in large numbers, like an army, from one plant or area to another, devouring foliage as they go.
- Armyworms have a wide range of host plants, including many common home garden vegetables and herbs.
- Adult armyworm moths lay their eggs in clusters on the undersides of leaves or on nearby plant debris.
- Armyworm larvae can vary in color, ranging from green to brown or black, and have distinctive stripes along their bodies.
- Armyworms are most active during the night, making it difficult for gardeners to spot them during the day.
- Natural predators, such as birds, ladybugs, and parasitic wasps, can help control armyworm populations in the garden.
- Some organic control methods for armyworms include Bacillus thuringiensis (Bt), spinosad, and neem oil.
- Gardeners can also use physical control methods, such as hand-picking armyworms off plants or using barriers like collars around seedlings to prevent armyworm damage.
- Implementing good garden hygiene, like removing plant debris and keeping the garden free of weeds, can help reduce the risk of armyworm infestations.
Luckily, armyworms are not invincible. There are several all-natural methods that you deploy take to handle your cutworm infestation—and measures that you can take to keep them from coming back in the future.
There is no reason to use harmful pesticides or chemicals to kill cutworms in your garden. Not only will these pesticides and chemicals be all over the food you are growing in your plots, using unnatural substances to rid your garden of pests is completely unnecessary, as there are natural methods that do the trick. One method you can take is to hand-pick the little guys at night. Drop them into soapy water to kill them, or stomp them with your feet. Just don’t throw them across the lawn, as they are known to crawl right back where they started and get back to the job at hand—chewing up your plants.
One method that has had fantastic results is a pest spray that contains spinosad. Spinosad seems safe enough to the worm, so they keep eating the plant as if nothing is different about it. Once they ingest the spinosad, however, it’s all over for them. They will die within two days of eating a leaf that has been sprayed with spinosad. Spinosad will not harm other beneficial insects in your garden, either, so don’t think twice about it. Just spray away and go on about your business.
BT Dust (bacillus thuringiensis)
Another method for killing cutworms that is tried and true is to sprinkle garden dust in the affected area. Garden dust, or bacillus thuringiensis (BT), is safe and non-toxic to humans and animals but very effective at killing cutworms and other caterpillars. Though BT will take care of the cutworm infestation, it has no effect on cutworm eggs, so you may have to treat your garden with BT multiple times before the situation is rectified to make sure you’ve treated for each generation of cutworm larvae. The only downside to BT dust is that it can kill butterflies, too. Aside from being beautiful and friendly, butterflies are excellent pollinators.
Diluted neem oil is a known worm killer that will kill larvae and eggs as well. Find a neem oil spray, or make your own and spray the affected plants down thoroughly—making sure to cover the entire plant, including the undersides of leaves. Neem oil is all-natural and safe to spray on plants that you plan to eat eventually. The one downside to neem is that it is not the most powerful insect killer out there. It should do the trick for smaller cutworms, but it might not get the job done against bigger ones who are plump off of your garden’s foliage. One way to assure that the neem has a fighting chance is to make your own diluted neem spray because you can adjust the strength accordingly and make sure that it’s strong enough to give the bigger worms a run for their money.
Releasing beneficial parasitic nematodes into your soil is another excellent method for ridding your garden of cutworms and armyworms. Nematodes love snacking on the eggs and larvae of more than 200 common garden pests, so releasing them into your soil is a good idea, even if you are not seeing signs of cutworms at the moment. Nematodes are not harmful to humans or animals, but worm eggs and pupae don’t stand a chance against them. Releasing the nematodes won’t kill the adult cutworms, so you will want to use them in combination with something that does, like BT dust. Nematodes are to prevent future outbreaks of cutworms in your garden. They specifically target the eggs and larvae of the cutworms, killing off future generations before they have a chance to wreak havoc on your garden beds.
Another way to defend against cutworms is to attract natural predators to your garden. How does one go about doing that, you may ask? When planning out your garden, be sure to add in some plants whose blooms attract birds and beneficial insects, such as ladybugs and wasps. In fact, you can even purchase Trichogramma wasp eggs on Amazon or at most gardening shops. These wasps won’t necessarily kill all the full-grown worms that are feasting on your harvest, but they will kill all their kids. Trichogramma wasps lay their eggs inside of cutworm eggs, which kills the larvae.
Creating a bird sanctuary around your garden can have multiple benefits. Not only will they feast on the cutworms and other pests that reside in your garden, they also help to pollinate your plants. Attract birds with bright colors, delightful scents, and eye-catching textures by knowing what to plant in the patch. This comprehensive article Landscaping to Attract Birds and Wildlife will point you in the right direction as to what plants to focus on to bring more birds and other beneficial pollinators to your garden.
Cutworms love cornmeal, and if it’s presented to them, they just can’t help themselves. They eat it until there is no more to eat. The problem is, they cannot digest it. That doesn’t stop them from trying, however, and most (but not all) cutworms will literally eat themselves to death. Don’t put out too much cornmeal, though, as cutworms are not the only pests that enjoy it immensely.
Pesticides and bug sprays are not always the answer. In fact, they often do more harm than good. Unless your garden is strictly for aesthetic enjoyment and you don’t plan to eat any of the yields, pesticides should be the last option you reach for when pests are infesting your garden beds. With so many natural options to choose from, there is no reason why gardeners should need to use a chemical solution. Cutworms can devastate a garden if left unchecked, but now you know what to look for and how to nip it in the bud without using harmful chemicals and sprays.
Vegetables and Herbs Susceptible to Armyworms / cutworms
|Plant||Plant Type||Scientific Name|
|Carrot||Vegetable||Daucus carota subsp. sativus|
This list is not comprehensive, but it includes some of the more common plants that armyworms may infest that people like to grow in gardens at home.
Learn more about fighting armyworms/cutworms: