The cabbage white butterfly is drawn to brassicas—cabbage, cauliflower, broccoli, bok choy, kale, brussels sprouts—members of the cabbage family. A single caterpillar can decimate a young plant. Here’s how to get rid of cabbage worms in your home garden—naturally.
Once upon a time, when I was a little girl, I proudly showed my grandma a wee sweet caterpillar. Instead of oohing and aahing over my find, Grandma snatched the wooly thing out of my hand and smashed it underfoot. To her, it was simply a garden pest, but I was crushed.
I like to think that I’d never do such a thing in front of a child, but I can and do handpick pests in the privacy of my own garden. Cabbage whites, those pretty white butterflies that flit around home gardens in the summertime, can wreak havoc in a garden.
The other day a cabbage moth flew by. I did the logical thing and snatched it out of the air. There were no witnesses to my cruelty or to the fact that I’d snatched a moth right out of the air. I have turned into my Grandma, albeit a ninja version of my grandma.
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There are some similarities between the different pests. The adults flock to plants in the cabbage family, brassicas like collards, cabbage, cauliflower, broccoli, bok choy, and kale, making it difficult to establish these plants in a garden. A single caterpillar can decimate an entire young plant, making them some of the most frustrating garden pests to deal with.
How to Get Rid of White Butterflies in the Garden
As a passionate gardener, I know how frustrating it can be to see those pesky white butterflies fluttering around your vegetable patch or flower beds. While they may look pretty, white butterflies can cause major damage to your plants if left unchecked. The larvae of these insects, known as cabbage worms, voraciously feed on the leaves of many crops and can quickly defoliate entire plants.
In this comprehensive guide, I’ll share the methods I’ve found most effective for controlling white butterfly populations in the garden, so you can protect your plants and maintain a healthy garden ecosystem
Identify the Culprits
The first step is identifying the type of white butterflies you are dealing with The two most common species found in gardens are
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Cabbage white butterfly (Pieris rapae) – This is the smaller of the two, with wingspan around 1 to 1.5 inches. The upper wings are white with distinct black spots, while the underwings are pale yellow with grey markings.
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Large cabbage white butterfly (Pieris brassicae) – As the name suggests, this species is slightly bigger with a wingspan reaching 2 inches. The wings are white with black markings on the forewings.
Both these butterflies lay their eggs on plants in the Brassica family, which includes cabbage, broccoli, cauliflower, kale and Brussels sprouts. Once the eggs hatch, the green caterpillars voraciously feast on the leaves before forming a chrysalis to transform into butterflies, thus completing their life cycle.
Remove Host Plants
Starve them by removing any unwanted Brassica weed plants. Butterflies detect these host plants and will lay eggs on them, allowing caterpillar populations to thrive. Eliminate these food sources to deter butterflies from congregating in your garden.
Use Physical Barriers
Floating row covers are a simple and effective way to form a protective barrier around your vegetables. The lightweight fabric prevents butterflies from reaching the plants to lay eggs while still allowing water, light and air to permeate. Ensure proper installation so there are no gaps for butterflies to sneak through.
You can also use netting to shield seedlings or smaller plants. Choose netting with hole sizes fine enough to keep butterflies out. Support the netting properly and check regularly for tears.
Handpick Eggs and Caterpillars
Closely monitor plants and handpick any eggs or caterpillars you find. Butterflies usually lay single pale yellow eggs on the underside of leaves. Caterpillars are velvety green worms. Squish any you spot to prevent them from multiplying. Check daily, as they can develop quickly.
Use Bacillus thuringiensis (Bt)
Apply Bt insecticide on plants as soon as the first eggs hatch. Bt contains bacteria that are toxic only to caterpillars, not beneficial insects. It must be reapplied frequently as it degrades rapidly. Always follow label directions carefully.
Encourage Natural Predators
Ladybugs, lacewings, parasitic wasps and some birds prey on white butterfly eggs and larvae. Avoid pesticides that would harm populations of these beneficial insects. Plant flowers that provide nectar and pollen to attract them. You can also purchase some predators from garden suppliers.
Interplant with Deterrent Plants
Some plants emit scents that deter cabbage butterflies, making them useful companions. Mint, thyme, sage, dill and garlic can mask the odor of Brassica crops. Marigolds also repel the butterflies. Interplant these around your garden borders.
Rotate Your Crops
Rotating crops in different areas of your garden each season helps disrupt the butterfly life cycle. Move your Brassicas to a new spot so any lingering pupae in the soil from last year won’t emerge near fresh host plants.
Time Your Planting
In some regions, cabbage whites overwinter as pupae and emerge as butterflies in spring. If you wait to plant brassicas until late spring or early summer, you can avoid the first wave of emerging butterflies. Just be mindful of your seasonal planting requirements.
Clean Up Thoroughly
Eliminate any leftover plant debris in your garden beds at the end of the season. Dispose of all fallen leaves and plant matter where white butterflies may have laid eggs. This removes potential overwintering sites for pupae.
Accept Some Damage
Even with the best control methods, you’ll likely still see some white butterflies and a few chewed leaves. Unless it’s a serious infestation, a small amount of cosmetic damage to outer leaves won’t affect the plant much. But stay vigilant for major outbreaks.
By implementing a combination of these methods, you can keep white cabbage butterflies in check and protect your garden from extensive damage. Consistent monitoring, exclusion and encouraging natural predators are key to long-term management. With some perseverance, you’ll be rewarded with a bountiful harvest.
Here are some final tips for managing white butterflies successfully:
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Cover young seedlings immediately to shield them early on.
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Remove any wild mustard plants and burning them to destroy eggs.
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Introduce predators early in the season before infestations start.
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Be prepared to remove badly infested plants to prevent further spreading.
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If using netting, monitor for and repair tears promptly.
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Always check undersides of leaves, as that’s where eggs are laid.
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After harvest, solarize soil in bed to kill any lingering pupae.
With the right techniques, you can reclaim your garden and savor delicious, homegrown brassicas. Don’t let those fluttering pests steal your harvest this season!
How to prevent cabbage white butterflies from moving in
An infestation of these pests can wipe out a young crop of cabbage or kale in days. Prevention is the best way to avoid that loss. There are a number of natural tactics you can use to prevent these pests from taking up residence.
- A floating row cover or other fine netting can prevent cabbage moths from accessing leaves to lay eggs, thus breaking the cycle.
- Another idea for a physical barrier is to cover individual plants with upcycled mesh trash cans.
- Consider planting some cabbage moth trap plants to draw the cabbage worms away from your vegetable garden. A good choice in this case is a perennial tree collard. Planted some distance from your garden, you can let the moths go to town on these “sacrificial” plants.
- Interplanting brassicas with dill and lavender as companion plants can deter cabbage butterflies. More on companion planting here.
- Give plants a good dusting of diatomaceous earth regularly. Even if a butterfly manages to lay eggs on the plants, the soft-bodied caterpillars won’t stand a chance.
Natural predators are good bugs that will help get rid of the bad pests. Beneficial insects that help control cabbage worms in brassica crops include:
- Ladybugs: These predators feed on a variety of soft-bodied pests, including the eggs and larvae of cabbage worms.
- Parasitic Wasps: These tiny wasps lay their eggs inside cabbage worm larvae, and the hatching wasp larvae consume the host from the inside.
- Lacewings: Lacewing larvae, also known as aphid lions, prey on cabbageworm eggs and young larvae.
- Ground Beetles: These beetles hunt and feed on cabbage worms and other ground-dwelling pests.
- Hoverflies: Hoverfly larvae are voracious predators of aphids, small caterpillars, and other pests, helping to keep cabbageworm populations in check.
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Let’s focus on the one cleverly named “cabbage worm.”
Cabbage moths are to brassicas as hornworms are to tomatoes. They are THE pest that you need to know about if you plan to grow brassicas.
White cabbage butterflies lay their eggs on brassica plants, often on the underside of leaves. They are initially white, but turn yellow as they mature. The tiny eggs hatch in about seven days.
Tiny cabbage worms emerge from the eggs and begin immediately chewing on the leaves. The first telltale signs of damage will be shallow, grayish markings in the leaves. At this stage, the worms aren’t big enough to chomp all the way through a leaf. Not to worry, though—it will happen quickly enough!
Cabbage worms are a lovely velvety green. They blend in easily in a bed of green plants.
These worms tend to hide on or near the veins of leaves. When they’ve reached maturity at about an inch or 1-1/4″ long, they’ll pupate in preparation for their transformation into a cabbage white butterfly.
The chrysalis is often attached to the host plant or in nearby debris. In this case, it has attached itself to the planter my kale is growing in.
Eliminate Cabbage Worm & Cabbage Butterfly In The Garden | Organic Pest Control | Pieris rapae
FAQ
How do you repel white butterflies?
Some gardeners suggest crushing egg shells and placing them around the brassicas, another cuts out butterflies from white ice cream containers and places them around the vegetable garden and believes they are a very good deterrent.
What is the best homemade spray for white butterflies?
Finally, if your netting isn’t doing the trick, or if you want a little extra protection, you can spray the leaves of brassica plants with a homemade garlic spray to deter the butterflies. Simply chop up raw garlic and infuse with water for a day or two.
What is the best insecticide for white butterflies?
Btk (Bacillus thuringiensis kurstaki) can effectively controls this pest, but it must be applied about every seven days beginning after the larvae first appear.
How do I get rid of butterflies in my garden?
Effective Methods to Get Rid of Butterflies and Their Larvae
Natural Deterrent Herbs: Plant lavender, sage, and peppermint nearby as their scents naturally repel many butterfly species. Biological Control: Encourage natural predators like birds and beneficial insects that feed on caterpillars.