You’ve planted baby cabbages and kales and collard greens in your vegetable garden. You’ve delighted in the bright green of their leaves, their frilled edges, and looked forward to garden-fresh cabbage wraps and kale smoothies. One day, you step outside to check on your leafy greens, and the bright green leaves are spotted with holes. The frilled edges are lined with what look like teethmarks. What’s happened to your future salad?!
Your baby brassicas have fallen victim to pesky cabbage moths and cabbageworms, common garden pests that can wreak havoc on your tenderest leafy greens if left unchecked. Cabbage moths and cabbageworm butterflies lay hundreds of eggs on your cabbage leaves. These eggs hatch and release their larvae, little green caterpillars, the real agents of destruction.
But don’t worry. You don’t have to sacrifice all your leaves to the cabbage pest chaos. We’ve got you covered with this comprehensive guide on cabbage moth control, including preventative measures and organic solutions to keep your plants healthy and pest-free.
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WHAT PLANTS DO CABBAGE MOTH CATERPILLARS COMMONLY ATTACK?
This group of pests find plants in the Brassicaceae family, also known as cole crops, particularly irresistible. Brassica crops include cabbage, (obviously), plus kale, mustard greens, arugula, kohlrabi, broccoli, cauliflower, collard greens, turnip greens, Brussels sprouts, and rutabaga. You might even notice holes in your radish greens, since radishes are a root crop from this family.
Young plants in this family are generally the most vulnerable to attack. (Bugs have a preference for tender baby leaves, just like we do.)
SIGNS OF A CABBAGE MOTH INFESTATION
Cabbage moths and butterflies are not the real issue. It’s their spawn, the little caterpillars themselves. They hatch from their eggs and immediately start eating your cabbage plants, causing a lot of damage if not addressed promptly.
Here are the signs so you can be on the lookout:
- Small white butterflies or brown moths fluttering around your garden – The white butterflies, also called cabbage whites, will lay cabbageworm eggs on the leaves of your plants, and they’re usually active during the day. Grayish brown moths, which are active at night, lay eggs for cabbage moth caterpillars or another very similar pest called cabbage loopers.
- Irregular holes and chewed edges on leaves – Cabbage moth caterpillars, cabbage looper larvae, and cabbageworms typically hang out on the underside of leaves and feed from there. As soon as you notice holes in your leaves, flip them over for inspection. You’ll likely find little caterpillars hanging out. In addition to irregular-shaped holes and damage to the leaf edges that look like a much larger animal took a bite out of them, you may also see translucent sections on the leaves, where the caterpillars have left only a thin layer.
- Seedling reduced to stems and veins – I’ve had cabbageworms reduce newly planted kale seedlings to almost nothing in very little time.
- Small clusters of pale yellow eggs on the underside of leaves – The eggs can be hard to see because they’re so tiny, but they’re usually laid in clusters on the undersides of leaves or along leaf veins.
If you notice any of these signs, it’s time to take action to protect your cabbage crops. If left unchecked, a severe infestation can lead to stunted growth and even plant death (dun dun dun!).
THE LIFE CYCLE OF CABBAGE PESTS
It helps to have a general understanding of their life cycle so that you can more effectively control cabbage moths, cabbage loopers, and cabbageworm butterflies. They all go through four basic stages: egg, larva, pupa, and adult.
Here’s an overview: The adult moths lay their eggs on the leaves of brassicas. After a few days, the eggs hatch and release the little caterpillars. Cabbage worms are usually pale green with a velvety texture and look very similar to cabbage loopers. Cabbage moth caterpillars are green to brownish-black.
These guys feed voraciously on the leaves of brassicas, growing in size as they consume plant tissue. Once they reach maturity, they enter the pupal stage and form a cocoon around themselves. After a week or two, adults emerge from the cocoons, restarting the life cycle.
You can have several overlapping generations in your garden each year starting in early spring. If you live in a warmer climate, you can have as many as 8 cycles!
10 WAYS TO CONTROL CABBAGE MOTHS
The very first step in pest prevention and control is to visit your garden every day—that way, you can notice early signs of a problem and take measures before a couple bugs turn into an invasion. Early detection is key to preventing pests from causing significant damage. Beyond that, there are some other easy ways to control current cabbage pest populations and prevent infestations in the future. (Note: Most of these methods should work for cabbage moths, cabbageworms, and cabbage loopers.)
1. Remove Manually
One effective natural method is handpicking. Inspect your plants regularly and remove any pests you find. Wear gloves and drop the caterpillars into a bucket of soapy water to prevent them from returning to the plants.
It’s also a good idea to prune leaves that are heavily damaged by pests. Make sure to toss these leaves in the trash (they might have eggs on them). This method is time-consuming but can be highly effective, especially in small gardens. Repeat daily.
While you’re searching for pests, go ahead and clean up any plant debris like fallen leaves in the growing space. The smell of decaying plant material apparently attracts cabbage moths to your garden.
2. Spray Bacillus Thuringiensis (Bt)
Bt introduces a naturally occurring bacterium that kills caterpillars after they ingest it. Bt is safe for humans, beneficial insects, and most other organisms. To apply something like Captain Jack’s B.t spray, you simply spray it on the leaves of your plants, focusing on areas where caterpillars are present. It’s best to spray in the evening because Bt degrades in the sunlight. Repeat the application every week as needed, especially after rainfall (which will wash Bt off the leaves).
3. Install Physical Barrier
One of the best ways to prevent pest infestations is by using a physical barrier like a floating row cover or garden mesh draped over garden hoops. This stops the adult cabbage moths from accessing your plants and laying their eggs. The idea is to cover the entire garden space in a fine mesh netting that’s secured at the bottom with landscaping pins or clamps. (Make sure to leave no gaps.)
The small holes in the mesh allow air, sunlight, and water through, but keep moths out. You can pull the mesh back when needed to tend and harvest, but otherwise, you’ll leave these in place throughout the growing season (unless you have fruiting plants that need to be pollinated).
This method not only protects your plants from hungry, hungry caterpillars, but also shields them from other pests and adverse weather conditions. The best time to install a physical barrier is the day of planting, especially since young plants are particularly vulnerable.
4. Add Decoy Moths
Cabbage moths are supposedly territorial little creatures, so some gardeners place decoy moths around their garden beds. You can make your own using the template below and following the instructions at The Seed Collection. Other gardeners wrap foil around the base of their cabbage plants, claiming the reflective surface confuses the moths and makes it difficult for them to locate your plants.
5. Plant Red and Purple Cabbage Varieties
Pests are less likely to lay their eggs on and attack red and purple vegetables than green ones. One theory why is that it’s harder for them to camouflage their little green bodies on red and purple leaves. They prefer green kale and green cabbage plants so that predators can’t spot them easily. Another theory is that the flavonoid that makes red and purple veggies red and purple (anthocyanin) is actually toxic to caterpillars. (Don’t worry—it’s really good for us!)
6. Companion Plant
Companion planting is an age-old gardening practice that involves growing certain plants together to benefit one another. When it comes to cabbage moth control, there are specific companion plants you can utilize to deter these pests.
Herbs with strong scents like thyme, mint, nasturtiums and marigolds, plus plants from the onion family like garlic and onions, help keep cabbage moths and other pests at bay, so it’s a good idea to have these growing near your Brassicas.
7. Attract Beneficial Insects
Flowering herbs like rosemary, sage, anise hyssop, yarrow, dill, and marigolds attract beneficial insects that feed on these pests to your garden. Natural predators that can control cabbage moth populations include ladybugs and parasitic wasps (these wasps lay their eggs inside the caterpillars, effectively killing them). Make sure to grow lots of flowers in your vegetable garden to provide nectar and pollen for these beneficial insects.
8. Use Diatomaceous Earth
Diatomaceous earth is considered a nontoxic way to target pests like the imported cabbageworm and any other soft-bodied critters. You sprinkle the powder on the leaves of your plants and around their bases, and the powder dehydrates pests so that they’re dead within 48 hours. Reapply after rain.
9. Use Arber’s Organic Bio Insecticide
Arber has created a line of organic products that work for indoor and outdoor plants and that target all kinds of pests–everything from aphids and gnats to caterpillars and stink bugs. Their bio insecticide uses good bacteria that won’t harm bees and other beneficial insects.
Spray the mixture on the leaves of your affected plants.
10. Spray Neem Oil
Neem oil is derived from the seeds of the neem tree and acts as a natural insecticide for soft-bodied pests. Dilute neem oil with water according to the instructions on the bottle and spray it on your cabbage plants (or get Captain Jack’s ready-to-go spray). This spray not only kills cabbageworms but also disrupts their feeding and reproductive capabilities.
GOOD LUCK WITH CABBAGE MOTH CONTROL
I hope these tools and techniques help you effectively control these pests and keep your plants healthy and pest-free. First and foremost, remember to visit your garden every day. I always say the gardener’s shadow is the best form of organic pest control.
Inspect your kale and cabbage plants for signs of pest presence and take immediate action when necessary. Keep your soil clean and dispose of fallen leaves and pest-damaged leaves in the trash. Practicing good garden hygiene can go a long way in protecting your plants from pest infestations.
Here’s to keeping your plants healthy all season long so you get to enjoy more delicious leaves than the pests do! Say bye bye to damaged leaves and hello to healthy, thriving leafy greens.