How To Get Rid Of Cabbage Worms And Moths


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Wondering how to get rid of cabbage worms in your garden?

Cabbage worms are small green caterpillars of the small white butterfly that feed on plants in the cabbage family. They are best controlled with BTK but there are other easy to use organic controls you can use to, keep reading to find out more.

Are you starting to find holes in the leaves of your cabbage, kale, broccoli or other brassica family plants?

Then there is a good chance you are having a problem with cabbage worms.

But don’t worry they can easily be controlled naturally and you can prevent them from destroying your garden crops!

Get Rid Of Cabbage Worms The Easy Way text overlaid on a photo of a green cabbage worm

What Are Cabbage Worms?

Cabbage worms also called imported cabbageworms are the larva of the cabbage white butterfly. But it’s more often called the cabbage moth in North America.

This is the most common pest when growing cabbage, broccoli, kale, cauliflower, and Brussels sprouts.

Types Of Cabbage Worms

When people talk about cabbage worms there are two species they could be describing depending on where you live.

Small White

Small white butterfly (Pieris rapae)
Small white butterfly (Pieris rapae)

The small white (Pieris rapae) gets its name from the color of the adult butterfly. They are white with a small black dot on its wings.

These are the butterflies you see flying around your cabbage plants through the summer. Growing up we called them cabbage moths but surprise they are actually a butterfly.

This pest is spread through Europe, Asia, and South America. It was accidentally introduced to Australia, New Zealand, and North America.

Large White

Large white butterfly (Pieris brassicae)
Large white butterfly (Pieris brassicae)

The large white (Pieris brassicae) is similar in appearance to the small white but larger and also has large black patches at the tip of the wings. It’s commonly found in Asia, Europe, and Africa.

But was also accidentally introduced to New Zealand and Australia. There have been sightings of it in the USA and South America although it’s not commonly found yet.

How To Identify Cabbage Worms

Right: Cabbage worm from the small white butterfly. Left: Cabbage worms from the large white butterfly.
Right: Cabbage worm from the small white butterfly. Left: Cabbage worms from the large white butterfly.

Cabbage worms from the small white are a small light bluish-green caterpillar. Often having a few faint yellow stripes. With their color and velvety appearance, they blend in well with the cabbage leaves.

Unlike cabbage worms, the cabbage looper raises and lower their bodies as inchworms do and this makes it easy to tell the difference between the two pests.

Although the large white butterfly looks similar to the small white the caterpillars are different.

Large while caterpillars are yellowish in color with a brown head. As they grow they start to develop brown spots along their sides.

Lifecycle

Cabbage worm eggs
Cabbage worm eggs

Starting in the spring cabbage moths lay their eggs on the underside of plant leaves.

The small white lays one egg at a time whereas the large white tends to lay many eggs at a time

Cabbage worm and pupa from the small white butterfly.
Cabbage worm and pupa from the small white butterfly.

When the eggs of the small white hatch they look like tiny green worms with dark heads. This is where the name cabbage worm comes from.

As it feeds it grows through 5 in instars (growth stages) where it molts its skin and becomes more evenly green in color.

When its growth is completed it will form a mottled grey or yellowish pupa and emerge as a small white butterfly.

Cabbage worms from the large white butterfly.
Cabbage worms from the large white butterfly.

The lifecycle of the large white is almost the same except for the coloration of the caterpillars.

What Do They Feed On?

Damage on the head and leaves of cabbage from cabbage worms.
Damage on the head and leaves of cabbage from cabbage worms.

Given the name cabbage worm, it’s obvious that this pest loves cabbage plants. But they will feed on anything in the cabbage family.

This includes:

  • Cabbage
  • Cauliflower
  • Collard Greens
  • Broccoli
  • Broccoli Romanesco
  • Bok Chou
  • Brussels Sprouts
  • Horseradish
  • Kohlrabi
  • Mustard Greens
  • Napa Cabbage
  • Radish
  • Turnips
  • Rutabaga
  • Tatsoi

How To Get Rid Of Cabbage Worms

While cabbage worms can feel very frustrating to deal with there are easy ways of controlling them before they wipe out your garden crop.

1. BTK

BTK (Bacillus thuringiensis) is the most popular way to control cabbage worms naturally.

Often called BTK or BT this is a bacteria that is naturally found in soil. Spraying it on your plants won’t harm them but it will kill the caterpillars that feed on them.

BTK gets into their system when they eat leaves that have been sprayed. Then it disrupts the digestive system of the caterpillar causing it to die.

I find applying BTK weekly to any plants in the cabbage family in my garden keeps them free of caterpillar damage.

You can get BTK here.

2. Diatomaceous Earth (DE)

Another way to get rid of cabbage worms is to use food grade diatomaceous earth sprinkled over your plants.

This powder cuts and the skin of insects that crawl through it and causes them to dry out and die.

You can get DE here.

3. Natural Predators

Cabbage worms have many natural predators such as parasitic wasps, yellow jackets, spiders, green lacewings, predatory beetles and birds.

Encouraging a wide range of natural wildlife in your garden can help to lower the number of pests you have eating your vegetables.

4. Hand Picking

If you have just a few plants handpicking can be a good option. Look on both the top and bottom of leaves every day for eggs and caterpillars.

Crush any eggs you find and pick off the caterpillars. They can be fed to your chickens or drowned in some soapy water.

Prevention

If you don’t want to use any sprays in your garden, even natural ones then the easiest way to control cabbage worms is to use a floating row cover.

Often these are thought to be for frost control only but they also come in lightweight types made for bug netting.

You’ll want to use them over hoops in your garden so the netting doesn’t touch the plants.

This will keep the white moths from landing on the plants to lay eggs.

Growing cabbage is really easy when you take these preventative measures early in the season.

Active Time
20 minutes

Total Time
20 minutes

Difficulty
Easy

Instructions

  1. BTK is the easiest way to get rid of cabbage worms in your garden. This natural bacteria upsets the caterpillars’ digestive system causing it to die. Spray on your plants following the directions on the bottle (I do every 1-2 weeks). Remember to reapply after it rains.
  2. Diatomaceous earth is another effective way to deal with cabbage worms. This natural powder is sprinkled over your plants. It damages the skin of the caterpillars when they crawl through it causing them to dry out.
  3. Hand-picking is another good option if you have a small garden. Check the cabbage plants every few days remembering to check the top and bottom of the leaves. Crush any eggs you find and pick the caterpillars into a can of soapy water.
  4. Creating an environment that attracts beneficial insects to your garden can really help lower pest insects. Plant a variety of herbs and flowers that attract spiders, lacewings, predatory beetles and birds.

Preventing Cabbage Worms

  1. If you want to prevent cabbage worms from getting at your plants the best thing to do is to cover them with bug netting as soon as you transplant the seedlings into your garden. Make sure to suspend the bug netting over the plants with hoops so that butterflies can’t land and lay their eggs through the cloth.

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