Don’t let cabbage worms destroy your garden; learn how to get rid of cabbage worms before!
Cabbage worms are a common pest in the garden, and they cause significant damage to your plants. If you spot one in your garden, you need to know how to get rid of cabbage worms.
Almost every year that I grow cabbage (which is yearly), I have a battle with cabbage worms. This year, I used more preventative measures and noticed a considerable decrease in the damage caused by these pests.
Despite their tiny size, I’m always shocked by the vast damage they cause.
Seriously, I’ve lost entire heads to these small little larvae.
So, if you’re sick of losing brassica crops to cabbage worms like I am, here is what you need to know about getting rid of these pests in your garden.
What Are Cabbage Worms?
The name “cabbage worms” is a generic term for several species of small, green caterpillars that love to eat cabbage and mustard family plants, known as the brassica family. If it’s part of the cabbage family, the worms will likely eat them.
Cabbage worms are the immature, larvae form of cabbage moths. If you see small, white butterflies fluttering around your garden, don’t be surprised if you also find cabbage worms. White butterflies are often called “cabbage moths” or “cabbage whites,” even though they aren’t moths at all. Another caterpillar called the cabbage looper comes from a brown moth.
What Do Cabbage Worms Eat?
These plants love anything part of the brassica family, such as:
- Collard Greens
- Brussels Sprouts
- Mustard Greens
How to Identify Cabbage Worms
Cabbage worms are easy to identify on your plants. They’re small, green larvae with a few faint yellow stripes. Identifying the adult moth is easy as well; they’re white butterflies with a few black markings.
If you see these moths fluttering around your garden, chances are they’re laying cabbage worm eggs on your plants that will soon become caterpillars.
Try not to confuse cabbage worms with cabbage loopers; these are different pests. The worms are fuzzy and green with faint yellowing markings, but cabbage loopers are more yellow-green and don’t have legs in the center of their bodies.
I often get zebra caterpillars in our garden. These are black, white, and green, eventually turning into an American noctuid moth.
The Life Cycle of Cabbage Worms
It all starts when a cabbage moth lays eggs on your plant. The eggs look like white or yellow oblong dots that are almost always on the underside of the plant leaves. These eggs are sporadic and solo, rarely in clusters or groups.
If you spot these eggs, squish them!
When the eggs hatch, the larvae emerge, and these are the real problem in your garden. The cabbage worms start to feed on all the surrounding plant matter, leaving holes throughout the leaves.
The worms continue to eat and grow for several weeks, and then they form a chrysalis for the worms to pupate into the adult cabbage moth.
Once the chrysalis hatches, the moth emerges, and the cycle starts again as the female moths lay eggs on the plants in your garden.
Damage Caused by Cabbage Worms
The damage caused by cabbage worms varies.
In some situations, the larvae only create small holes in the leaves that gradually expand to larger holes over time.
Other times, these pests completely destroy the leaves or the entire plant as the larvae grow larger in size and population. These larvae love to eat the bases of cabbage, cauliflower, or broccoli heads.
At times, cabbage worm damage is only cosmetic, but if these pests find your seedlings, the damage is often significant. These caterpillars continue to grow and feed until they’re old enough to turn into the next stage of growth.
How to Get Rid of Cabbage Worms: 7 Tricks
Once you identify that you have cabbage worms in your garden, you need to get the population under control. Leaving them alone will result in the total destruction of your plants.
Trust me; I tried that.
Luckily, there are several ways to get rid of cabbage worms in your garden!
1. Remove Eggs and Cabbage Worms by Hand
The first way to get rid of cabbage worms is to manually remove them from your cabbage heads. While you might find this a bit gross, squishing or removing pests when you see them is often the most effective way to stop the population from expanding.
Inspect your plants daily, and if you see any eggs or worms, remove them. Remember that eggs and worms are often found on the undersides of leaves or tucked into the new growth at the plant’s center. Keep a bucket of soapy water nearby and drop the garden pests you find into the soapy water.
Cabbage worms lay along the center vein because they blend well with the plant. Also, watch out for the “frass” or fecal matter the worms leave behind; it’s a key sign that a cabbage caterpillar is nearby.
As mentioned above, these eggs are oblong, tiny, whitish, or yellowish eggs. You’ll only see a single egg at a time; if you find a group of them, they’re more than likely ladybug eggs. Leave those alone!
2. Use Cornmeal
Here is one of the old gardeners’ tricks to get rid of cabbage worms.
Supposedly, if you dampen the cabbage leaves with water and sprinkle cornmeal over them, the caterpillars will die when they eat the cornmeal. It causes their bodies to swell and die.
I’ve personally never tried this method, but what I like about it is no adverse effects can come from giving it a try. It’s easy and cheap, so why not give it a try?
Years ago, farmers sprinkled rye flour over cabbage plants in the early morning to dehydrate the active cabbage worms. Maybe, our ancestors knew what they were doing!
3. Make a Homemade Garden Spray
Try making a homemade garden spray to kill the worms in your garden.
A mixture I’ve used successfully is 1/4 cup vinegar, 3/4 cups water, and one teaspoon dish soap. Spray this on the leaves’ tops and bottoms, but ensure you don’t saturate them.
This also isn’t appropriate to use on young seedlings. It’s best to test it on a small area of your plant to be sure the plant tolerates the garden spray. You can spray it where you see plant debris and signs of cabbage worm infestations on host plants.
4. Release Parasitic Wasps
If you need to get rid of cabbage worms, try releasing beneficial insects like parasitic wasps into your garden. These are natural enemies of cabbage worms and one of the easy ways to target these garden pests.
Parasitic wasps lay eggs inside or on top of other arthropods, like caterpillars and their pupae. They combat cabbage worms and even other caterpillars like the tomato hornworms.
After the eggs are laid on the caterpillar, they hatch and the wasp larvae feed on the host caterpillar, killing it.
It’s slightly brutal but effective against cabbage worms. Trichogramma wasps are easy to find and won’t bite or sting – you won’t even notice them in your garden.
5. Spray with B.T.
Bacillus thuringiensis, or Bt, is a naturally occurring, soil-dwelling bacteria that you often find in organic pesticides. Most importantly, Bt kills caterpillars, and it’s only toxic against the larvae of the moths.
When the larvae eat leaves coated with Bt, it causes them to stop eating and eventually die. Many organic gardeners use this to control cabbage worms that infect brassica plants.
No matter what type of Bt you want to use in your garden, make sure you follow the directions on the container. It’s best to apply Bt in the evening hours because it rapidly degrades in the sunlight and washes off with rain or water. It’s most effective after two applications.
6. Spray with Neem Oil
Neem oil is something that all organic gardeners need to have on hand; it’s a plant-based oil that’s extracted from the seeds of the India-native neem tree. It works well against small, soft-bodied insects like cabbage worms, aphids, and thrips. When applied directly, neem oil coats their bodies, kills them, or interferes with their feeding.
Neem oil also helps to repel cabbage moths, so some like to spray it routinely on their garden.
However, to be honest, this isn’t the most effective measure to get rid of cabbage worms if you have a large infestation. It does work to repel cabbage moths if sprayed regularly in your garden as a preventative treatment. There are limited choices for organic garden pest control sprays, so neem oil is a solid choice.
Typically, you want to use neem oil in conjunction with other control methods. That’s when it will be most helpful to get rid of cabbage worms.
7. Sprinkle Diatomaceous Earth on the Leaves
One of the many ways to use diatomaceous earth is to sprinkle it on your brassica plants to kill caterpillars.
Use food-grade diatomaceous earth only and sprinkle it over your plants. DE is crushed up fossils, and when caterpillars crawl over the DE, the power cuts through the skin of insects. Then, it causes them to dry out and die.
8. Bring in Some Ducks
I often use my chickens to turn over my garden before planting, but ducks are a highly effective way to get rid of cabbage worms in your garden. Ducks love to eat the worms when able, so try containing them in the area with some fencing.
Ducks will spot the little green worms and beeline for them. However, I suggest leaving chickens out of this duty. Chickens will enjoy eating the worms AND cabbage heads. Ducks work as long as you have adult plants not young plants, which the ducks may consume entirely.
When you think about this, it’s one of the best natural methods for pest control. Ducks and other homestead animals eat these pests, so why not take advantange of it?
How to Prevent Cabbage Worms
It’s no surprise that cabbage worms cause a lot of damage in your vegetable garden. They are one of the most common pests gardeners experience. It’s best to work on prevention, which always tends to be easier than trying to get rid of the worms and adult butterflies from your garden.
1. Plant More Red and Purple Cabbages
Planting a mixture of red and red cabbage varieties in your garden will help attract fewer cabbage moths to your garden.
Many gardeners say that their purple cabbage and red kale have significantly less damage caused by cabbage worms than their green varieties. The theory is that the green-colored pests understand they cannot camouflage on a purple or red plant, so they avoid them.
Other studies show that anthocyanin, an antioxidant flavonoid that makes veggies red, purple, and blue-pigmented, is mildly toxic to caterpillars. In some cases, these colors are believed to deter larger pests like squirrels.
2. Invite Beneficial Insects
Not all garden pests are bad; you want beneficial insects in your garden. All insects have enemies, so if you invite all the good ones to your garden, they’ll take care of the bad ones.
I mentioned releasing Trichogramma wasps, but you also can release lady beetles, yellow jackets, spiders, and green lacewings. These are natural predators of cabbage worms.
3. Use Floating Row Covers
One of the best preventative measures against cabbage worms and moths is to use floating row covers when you plant your seedlings. Floating row covers prevent the adult moths from laying eggs on your plants, beginning the cycle.
Row covers stop pests from accessing your plants; many gardeners use these all over their gardens. Some row covers are used to stop insects, while others are meant for frost protection or shade cover.
You can use the same design I made for my DIY hoop house to cover my cabbage plants to protect them from the moths. All you need is some screws, a drill, and PVC pipes or steel-coated tunnel supports.
Related: $20 Simple DIY Mini Hoop House
4. Incorporate Companion Planting
Companion planting and polyculture, planting more than one crop together, is a great way to deter cabbage moths from finding your plants. Not only does polyculture increase the biodiversity of your garden, but these plants also attract more beneficial insects and reduce the spread of pests in your garden.
Try planting different flowers and herbs with your brassica plants. Herbs and flowers that deter cabbage moths include:
On the other hand, companion plants goes hand-in-hand with trap crops. You might plant some trap crops in your garden that cabbage moths and worms LOVE, like nasturtiums. The pests go to these crops instead, leaving your cabbages alone.
I suggest incorporating at least one (or more) trap crop in all of your garden beds.
5. Spray with Tansy Oil
Another natural preventative measure that you can use is spraying crops with tansy oil. It’s natural, organic, and won’t hurt your plants.
This is a preventative treatment, so spray your plants BEFORE the cabbage moths find your plants. It’s supposed to be a deterrent.
6. Use Decoy Cabbage Moths
Another idea to get rid of cabbage worms is to use decoys. Cabbage moths are territorial and generally stay clear of other ones. So, it is useful to play decoys around your garden bed. It prevents the cabbage moths from laying eggs on the host plants.
Cabbage worms are more common than you think; I bet they’ve found your