It would make me very wealthy if I could keep track of all the times someone said they hated brussels sprouts as a child but now love them.
Bugs that feed on sap, like caterpillars, worms, and other small bugs, can’t get enough of cole crops.
Luckily, brussels sprouts have the ability to grow big, pretty leaves that people don’t usually use. Insects often attack this foliage first.
These days, it doesn’t really matter if the leaves look a little beat up as long as the heads are still there.
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Some of them might not bother the heads, but the damage they do can stop sprouts from forming or make them short, ugly, or even loose.
This guide will help you figure out what’s eating your plants (other than you), when to act, and what you need to do to keep your sprouts safe.
Growing a bountiful crop of brussels sprouts takes time, care, and patience. After months of tending to these hearty vegetables, it can be heartbreaking to go out to your garden and find ragged leaves full of holes. Something has invaded your sprouts and is feasting away! But don’t despair. With some detective work, you can figure out what pest is munching on your sprouts and take action to stop them.
Common Culprits That Attack Brussels Sprouts
Several types of insects are attracted to the large, luscious leaves of brussels sprouts. Here are the most likely suspects eating your sprout leaves:
Cabbage Worms
These green inch-long caterpillars are the larvae of white butterflies. They chew large irregular holes in leaves and burrow into sprout heads. Heavy infestations can skeletonize plants. Cabbage worms are a very common pest of brassica crops.
Cabbage Loopers
The larvae of grayish-brown moths, loopers are light green worms with white stripes down their backs. They eat leaves from the edge inward, resulting in scalloped-edged holes. Like cabbage worms, they can decimate sprout plants when populations explode.
Flea Beetles
Tiny black beetles that hop like fleas when disturbed. They chew small round holes or pits in leaves Heavy feeding makes leaves look like Swiss cheese These beetles can be especially damaging to young sprout transplants.
Slugs and Snails
They creep up at night and chew irregular holes with smooth edges in foliage. Their slimy trails on leaves are evidence of their presence. These mollusks thrive in cool, wet conditions.
Aphids
While they don’t actually eat holes in leaves, large populations of these tiny sap-sucking insects can stunt and distort plant growth. Honeydew they excrete also promotes growth of sooty mold.
Inspect Plants and Identify the Culprit
The first step in stopping the leaf eaters is to figure out which pest is munching your sprouts.
- Check undersides of leaves for caterpillars, slugs, and snails. Shake leaves over a sheet of white paper to dislodge small insects.
- Look for hopping flea beetles and crawling aphids on leaves.
- Check for slime trails and holes with smooth edges, signs of slugs and snails.
- Raggedy holes with messy edges indicate caterpillar damage.
- Small round pits point to flea beetles.
- Stunted, distorted growth can mean aphids.
Finding the actual culprits in the act is the best way to diagnose what is feeding on your sprouts.
Organic Ways to Control Brussels Sprouts Leaf Pests
Once you’ve identified the culprit, you can take organic steps to prevent further damage:
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Remove pests by hand. Simply pick off any caterpillars, beetles, slugs, or snails you find on your sprouts. Drop in soapy water or stomp underfoot. Be diligent as you will need to hand pick daily to control infestations.
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Use row covers. These fabric covers keep moths and butterflies from laying eggs on plants. Installing over sprouts right after transplanting prevents caterpillars.
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Apply parasitic nematodes. These microscopic roundworms attack soil-dwelling pests like flea beetle larvae and slugs/snails. They are safe for plants and many beneficial insects.
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Encourage natural predators. Attract birds, lady beetles, parasitic wasps, and other beneficials to your garden with pollen/nectar plants. They will help control pests.
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Trap slugs/snails. Set out boards or shallow pans of beer at night to attract and drown these pests. Or use iron phosphate bait. Diatomaceous earth sprinkled around plants deters them.
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Use insecticidal soap. Spray aphids directly to kill them quickly. This natural soap only kills what it touches, so repeat applications may be needed.
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Apply Bt (Bacillus thuringiensis). This organic pesticide specifically targets cabbage worms and loopers when they eat treated leaves. It must be reapplied after rain.
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Make repellent sprays. Strong smells deter many insects. Sprays made with things like hot pepper, garlic, and mint can drive away pests. Just spray plants thoroughly and repeat after rain.
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Practice crop rotation. Don’t grow brassicas like sprouts in the same spot each year. Rotating plant families confuses pests and disrupts egg laying.
Be Vigilant to Protect Your Brussels Sprouts
Left uncontrolled, most of these insects can quickly defoliate brussels sprout plants once populations boom. Checking sprouts frequently and taking action at the first sign of leaf damage is key. Hand picking pests, putting down slug bait, using row covers, releasing beneficial insects, and spraying organic pesticides can together provide a good defense against leaf eaters. With persistence and diligence, you can enjoy a bountiful harvest of fat, delicious sprouts this season despite these leafy pests. Don’t let the bugs win!
Best Practices to Avoid Pests
Every pest is different, but there are things you can do to discourage invertebrates from attacking your plants.
Brussels sprouts are part of the cabbage family (Brassicaceae). That means they’re susceptible to attack from any insect that prefers brassicas.
To avoid these insects in the garden, there are a few steps you can take.
First, crop rotation is always a good idea. Many pests overwinter in the soil and wait for spring to attack.
You should put something nearby that they like or that gives them food, or they won’t have anything to eat and will die.
Interplanting is also smart. This involves putting plants from different families next to each other. This can also make it harder for predators to identify the plants they like to target.
That’s 20 square feet of brussels sprouts. You could plant one next to something from a different family, like a nightshade.
Pests that like new potatoes won’t usually be interested in nearby sprouts because they don’t share many pests.
Remove weeds and debris from the garden to deny pests alternate hosts or a place to hide.
13 Common Brussels Sprout Pests
Do something right away if bugs are bothering your brussels sprouts. Let’s not waste any more time!
Here are 13 of the most common pests, and how to deal with them:
It’s a fact of life that if you garden, you WILL deal with aphids at some point.
I honestly don’t pay much attention to them unless it seems like my garden has more aphids than plants (okay, maybe that’s a bit of an exaggeration…).
Plus, aphids attract beneficial insects that will eat all kinds of even worse bugs. So there’s that.
Aphids are bad because they can spread diseases and because they reproduce quickly and use up your plants’ energy. If they weaken your plant, it becomes susceptible to all kinds of other pests and diseases.
The kinds of aphids that will attack brussels sprouts are known as Brevicoryne brassicae.
They can be dealt with in the same way as any common aphid. Our guide can walk you through it all.
Armyworms are related to cutworms, but the damage that they do is very different.
Three kinds of these worms, which are the young stages of some night-flying moths, can eat Brussels sprouts.
These are the beet armyworm (Spodoptera exigua), the Bertha armyworm (Mamestra configurata), and the Western yellow-striped armyworm (S. praefica).
They come in a range of colors, from light yellow to almost black, and can look solid, striped, or spotted. All are around an inch long.
The worms can burrow into the buds or heads and can skeletonize leaves. What makes them particularly irritating is that they tend to come in waves.
For a year or two you will hardly see any. It’s almost like they’re waiting for you to let your guard down. Then, one year it’s like an invading army of worms have breached your garden’s fortifications and taken over.
Weed control is important. The Russian thistle, purslane, mullein, lamb’s quarter, wild mustard, and pigweed are just a few of the “weeds” that can be host plants.
If you see them, pluck them off and drown them in soapy water.
If you’re experiencing one of those intense years, Bacillus thuringiensis v. kurstaki (Btk) is going to be your best friend. We talk a bit more about this beneficial bacteria below.
It works too, but you have to keep applying neem oil or insecticidal soaps to get them to touch the worms again and again.
Try alternating your treatments each year to improve effectiveness, and prevent the development of resistance.
These little caterpillars have lots of natural enemies including spiders, assassin bugs, damsel bugs, and minute pirate bugs.
Did you know that if you don’t have these beneficial bugs in your garden already, you can often buy and introduce them? Places like Arbico Organics carry live bugs in packs of 500, 1,000, or 2,000.
You can also use insecticides with spinosad or pyrethrins to help, but only do so if nothing else works.
The cabbage looper (Trichoplusia ni) is a green caterpillar that is about an inch long and can make brussels sprout leaves look more like lace than leaves.
They are very common in North America and can have more than one generation each year, so if you grow brassicas, you’ll probably run into them sooner or later.
When that happens, take a look at our guide on how to identify and eliminate loopers.
When I was a kid, I used to watch cabbage white butterflies dance around the plants in my backyard. I thought they were beautiful flying flowers that meant it was officially summer.
After that, I started growing brassicas. I still like them, but I’m not as excited to see them now.
Luckily, these don’t do much damage to brussels sprouts because they are most active in the summer. But they can still be found in crops in the spring and fall, so keep an eye out.
Adult Pieridae moths are white with dark brown or black spots on their wings. They are not the problem. It’s the larvae that you want to avoid, which are small green worms called imported cabbage worms.
These little worms chew their way into the heads, where they stick around and feed.
They eat the leaves of the plant, too, though that’s mostly just a cosmetic issue. In large enough numbers, however, they can skeletonize the foliage.
You can pick them off your plants by hand and drown them in soapy water if you don’t have too many.
Bacillus thuringiensis v. kurstaki (Btk) is also extremely effective against them, and many other types of worms and caterpillars as well.
There are multiple products on the market containing Btk, such as Bonide’s Thuricide.
Available at Arbico Organics in quart- or gallon-size ready-to-use containers or eight- or 16-ounce bottles of concentrate, simply spray every week or so when the moths are active.
If there’s one caterpillar out there that should make you nervous, it’s the cutworm. Some pests can hurt your plants for weeks or months, but a cutworm can kill your seedlings in just one night.
Cutworms are the larvae of various night-flying moths in the family Noctuidae. Brussels sprouts are most hurt when they are seedlings because they eat through the base of the plants and kill them.
You don’t have to worry about this pest as much once the stems get thicker and longer.
We have a comprehensive guide to help you figure out how to handle a cutworm situation.
The larvae of diamondback moths (Plutella xylostella) may be tiny, but they’re voracious eaters.
They also feed at the base of sprout buds, which hurts them so much that sprouts don’t form. They can also devour young seedlings rapidly.
The caterpillars are green and just a third of an inch long. Some have two prolegs at the back that make a distinctive v-shape.
The adults are light and dark brown with, as you might have guessed, diamond-shaped markings on their wings.
If you spot the adults or the larvae, act quickly. Bug killer works on these bugs, but you need to get rid of them quickly before they do too much damage.
Earwigs are easy to spot because they have sharp pinchers on the back of their bodies and long, brown bodies.
There are many different species out there, and not all of them do damage to vegetable plants. The one you need to look out for is forficula auricularia, which is one of the most common kinds.
Regardless of the species, earwigs are generally good for the garden because they eat aphids and other unwanted pests. That said, they can completely destroy a brussels sprout seedling in just a few days.
If you start your seedlings indoors, earwigs are nothing to be concerned about.
By the time you transplant, the sprouts will be large enough to withstand an attack. But if you plant seeds outside and you notice earwigs about, you’ll need to provide some protection.
Flea beetles, which are little insects from the Chrysomelidae family, are fairly common pests. They can cause some pretty substantial damage even though they’re quite tiny.
They are very small, so it can be hard to find them. It’s better to look for the damage they cause.
If flea beetles are eating your brussels sprouts, the lower leaves will have a lot of little holes nibbled in them. They don’t typically bother the sprouts or younger leaves at the top.
Damage that isn’t too bad (because we’re only worried about those sprout heads) is usually just cosmetic. But damage that is too bad can stop your plant from growing.
It can help to plant early or late in the year, use floating row covers, plant trap crops, or till the soil.
Our complete guide has all the information you need to learn more about how to find, stop, and get rid of this pest.
Leaf miners are the larvae of flies in the Liriomyza genus. The maze-like trails these little worms leave behind show where they’ve been by chewing through the leaves of different vegetables and plants for decoration.
The miners themselves aren’t anything to worry about when it comes to growing brussels sprouts. They do some cosmetic damage to the foliage, but they don’t harm the sprouts.
Both the adults and the larvae can spread disease, and the damage they leave behind makes it easy for bacterial and fungal diseases to grow.
Anyone who grows brassicas knows that fungal diseases are to be avoided at all costs.
For those who have dealt with these bugs before, the best thing to do is cover your sprouts with floating row covers in the fall. Miner adults don’t lay eggs on plants in the spring.
If you already have leaf miners in the garden, don’t worry about trying to get rid of them. Just keep a close eye out for signs of disease.
For more details on how you can identify and prevent leaf miners, head on over to our guide.
Root-knot nematodes seem more like a disease than a pest, to be honest. That’s because you can’t see them.
They are very small and live in the soil. They eat the roots of your sprouts and many other vegetables as well.
These roundworms from the Meloidogyne genus can cause serious damage, in both home gardens and commercial farm operations.
Root knot nematodes cause the roots of plants to become clubbed and malformed. One bad thing about this pest is that you won’t know you have an issue until it’s too late.
Above ground, the signs aren’t as clear-cut because they can look like a lot of different illnesses. Sprout foliage may wilt or turn yellow, and the plants may be stunted. They may even die.
Once your sprouts are infested with root-knot nematodes, they’re toast. You can’t cure the problem without killing the plant.
You can let an infected crop keep growing and hope for the best, but it might be better to pull the plants that have pests on them and treat the soil so that the pests don’t spread to other parts of your garden.
If you want to know how to tell if you have this problem and how to fix it if you do, check out our guide to root-knot nematodes.
Q&A – What is eating the foliage of my Brussel sprouts?
FAQ
What is making holes in my Brussel sprout leaves?
How do you protect Brussels sprouts from pests?
What animal eats brussels sprout leaves?
Do Brussels sprout bugs eat leaves?
Late-maturing Brussels sprout plant leaves are at a high risk of damage by these pesky insects. If you’re worried that a Brussels sprouts bug is eating leaves, there are a few key signs to look for. First, check the undersides of the leaves; you may see the bugs themselves, or you may notice the sticky residue they leave behind after feeding.
What do Brussels sprouts and spinach have in common?
Both are dark green leafy vegetables, which give them rich in soluble fiber and high magnesium content. They are also rich in other vitamins and minerals, such as iron, calcium and phosphorus and vitamins A, K and the B complex. They help reduce blood pressure, help protect eye health, strengthen immunity and contribute to the well-being of the nervous system.
What eats brussel sprouts?
Flea beetles, aphids, and three species of cabbage worms eat brussel sprouts and other cole crops. Cole crops include broccoli, cauliflower, Brussels sprouts, collards, kale, mustard greens, turnip greens, radishes, turnips, rutabagas and kohlrabi.
Why are my Brussels sprouts dying?
Bacterial and fungal diseases are the primary Brussels sprouts problems. Some of these just discolor or mar foliage, but others can cause defoliation. This becomes a problem in large amounts because it affects the plant’s ability to photosynthesize. Bacterial diseases spread quickly and thrive in moist areas.
How do I know if my Brussels sprouts are bad?
Look for signs of damage on the leaves. If your Brussels sprouts are being eaten, you will likely see signs of damage on the leaves. This damage can take a variety of forms, including holes, tears, or ragged edges. Check for pests on the leaves and stems.
Are Brussels sprouts a pest?
It’s the rare plant that encounters no pest or disease issues. Brussels sprouts are affected by the same insects that plague cabbage plants. A few of these include: Protect young plants from cutworms by putting a collar around the plants. You can prevent flying insect damage with a net or row cover over the crop.