A Complete Guide for Home Gardeners

Cabbage loopers can turn your lush garden into a buffet in a matter of hours. If you grow cabbage, broccoli, kale, or other leafy greens, these pests can quickly become your biggest headache. The good news is that you can control them without losing your entire crop.

In this guide, you’ll learn what cabbage loopers are, how to spot them, and proven methods to keep them under control. You’ll also receive practical prevention tips, ensuring your plants stay healthy throughout the entire season.

What Are Cabbage Loopers?

Cabbage loopers are one of the most common—and most frustrating—pests in the garden. These little green caterpillars get their name from the way they crawl, forming a “loop” with their bodies as they move. They’re actually the larvae of a brown moth, which lays its eggs on the undersides of leaves.

The first sign you might have cabbage loopers? Big, irregular holes in your plants. If most of the damage is showing up on your Brassicas, for example, Kale, cauliflower, broccoli, and cabbage, cabbage loopers are very likely the culprits. And fair warning: they’re not picky eaters, so they’ll happily snack on other greens too if they get the chance.

Young loopers are sneaky. They usually start by chewing on the undersides of leaves, which makes them harder to spot at first. As they grow, though, they leave behind big, ragged holes that are hard to miss. These little eating machines can cause more damage than most other garden pests, even tunneling into the developing cabbage head instead of sticking to just the outer leaves.

Another sign to look out for? Their droppings, cabbage looper poop, have the appearance of little greenish-brown pellets on plant leaves or around the plant’s base, which is a sign they’re feeding.

You might also find their eggs attached to your plants. These are small, round, and range from pale green to yellowish-white. Spotting and removing them early can save you a lot of trouble later.

The bad news? Once cabbage loopers discover your garden, they can be tough to kick out. They grow quickly, so catching them early is the key to keeping your harvest safe and your plants healthy.

How to Spot Cabbage Looper Damage

Before you can control cabbage loopers, you need to know what to look for. Signs of their presence include:

• Chewed Leaves: Look for round or irregular holes in leaves.
• Green Droppings: Tiny dark-green pellets on leaves or soil indicate feeding.
• Presence of Caterpillars: Flip leaves over and check for small green loopers.
• Adult Moths: Brown moths flying at night could signal a coming infestation.

Early detection gives you a head start on control methods and prevents severe plant stress.

What are Cabbage Loopers’ Favorites?

The traditional vegetable “hosts” for these pests are cole crops—broccoli, cauliflower, Brussels sprouts, and of course, cabbage. These plants are family to the Brassica family and are a favorite of many garden insect pests.

Cabbage loopers don’t stop there, though. They’ll even feast on the leaves of some of your favorite flowering garden plants.

Cabbage loopers will eat:

• Arugula
• Alfalfa
• Broccoli
• Beets
• Brussels sprouts
• Cabbage
• Cucumbers
• Celery
• Cantaloupe
• Collards
• Cauliflower
• Chrysanthemums
• Hollyhock
• Kale
• Lettuce
• Lima beans
• Mustard greens
• Potatoes
• Parsnips
• Peas
• Rutabaga
• Radishes
• Sweet potatoes
• Squash
• Snapdragons
• Spinach
• Sweetpeas
• Turnips
• Tomatoes
• Watermelons

Proven Methods to Control Cabbage Loopers

Now that you know what you’re dealing with, here’s how to take action.

1. Handpicking

This is the simplest and most natural method. Inspect plants every day and pick off any caterpillars you see. Drop them into a container of soapy water to eliminate them.

2. Floating Row Covers

Prevent moths from laying eggs by covering plants with row covers. Use a lightweight fabric that still lets sunlight and water through. Be sure to secure the edges tightly.

3. Beneficial Insects

Encourage natural predators like parasitic wasps, ladybugs, and lacewings. Plant nectar-rich flowers to attract these helpful insects.

4. Bacillus thuringiensis (Bt)

Bt is a natural, soil-dwelling bacterium that targets caterpillars. Spray it on your plants. This product is safe to use around humans, pets, and beneficial insects; however, before application, always read and follow the manufacturer’s directions on the label.

5. Neem Oil

Neem oil acts as a repellent and disrupts the pests’ life cycle. Mix according to label directions and spray in the early morning or evening to avoid harming pollinators.

6. Regular Monitoring

Check your plants at least twice a week. The sooner you catch the problem, the easier it is to correct.

7. Crop Rotation

Avoid planting cabbage or other brassicas in the same place each year. Rotating crops helps break the life cycle of cabbage loopers.

8. Clean Up Debris

Remove plant debris at the end of the season. Moths like to overwinter in garden litter.

Prevention Tips for Next Season

Controlling cabbage loopers is easier when you take preventive steps. Here’s what you can do:

• Start with healthy, pest-free seedlings.
• Space plants properly for good airflow.
• Keep weeds under control.
• Use trap crops like mustard to lure moths away.
• Rotate crops to reduce pest buildup.

FAQs About Controlling Cabbage Loopers

1. What plants do cabbage loopers attack?
Cabbage loopers target cabbage, broccoli, kale, cauliflower, and Brussels sprouts. They may also feed on spinach and lettuce.

2. Are cabbage loopers harmful to humans?
No, they are not harmful to humans. However, they can destroy your crops if left unchecked.

3. Can I use chemical insecticides?
Yes, but they should be a last resort. Many chemical sprays kill beneficial insects, too. Try organic methods first.

4. How often should I apply Bt?
Apply Bt every 7–10 days while loopers are active, or after heavy rain that might wash it off.

5. Will neem oil kill beneficial insects?
Neem oil is generally safe when applied in the evening. Avoid spraying during the day when pollinators are active.

6. How do I know if I have a serious infestation?
If most leaves have large holes and you see multiple caterpillars per plant, you have a significant infestation.

7. Can I grow cabbage without ever having loopers?
It’s possible, but unlikely. Using row covers from the start of the season gives you the best chance.

8. Do cabbage loopers have natural enemies?
Yes, parasitic wasps, birds, and predatory beetles feed on loopers.

9. How long do cabbage loopers live?
The caterpillar stage lasts about 2–4 weeks before they pupate into moths.

10. Is it too late to save plants with heavy damage?
If the plant still has healthy leaves and a strong stem, it can recover. Remove the loopers and give it a chance to regrow.

Conclusion

Cabbage loopers don’t have to ruin your garden. By learning to spot them early, using row covers, encouraging beneficial insects, and applying organic treatments like Bt and neem oil, you can keep your brassicas safe and thriving.

Remember, prevention is just as important as control. Rotate crops, keep your garden clean, and stay alert for signs of pests. A little daily effort goes a long way toward protecting your harvest.

With the right approach, you can enjoy crisp, healthy cabbage and other greens without sharing them with these hungry pests.