Broccoli (Brassica oleracea) is undoubtedly one of the most satisfying plants to grow. It’s a good feeling to head out to your garden in the morning and see big, beautiful heads of broccoli growing.
And, it’s even better when they’re ready for harvest, and you finally get to enjoy the fruits (veggies?) of your labors.
Except for one thing: what happens when you head out to your crop of burgeoning broccoli and see that the once big, waxy leaves are now chewed-up and full of holes?
Obviously, the culprit is some sort of insect. But, what kind of insect?
Don’t worry just yet—we’re going to run down the most common types of broccoli-loving insects and how you can prevent them from devouring your delicious broccoli before you have a chance to devour it yourself.
What is Eating My Broccoli Leaves?
If your broccoli leaves or heads are being eaten, you’ve got an insect problem. It could be cabbage moths, which are very common. It could also be diamondback moths or flea beetles. However, these insects can be easily thwarted with insecticide, by handpicking, or with row covers.
Common Pests That Love to Eat Broccoli
There are a few different pests that absolutely love to munch on broccoli or other Cole crops like cabbage, Brussel sprouts, etc.
These veggies are perfect for growing in raised beds or a garden, but that can make them susceptible to certain insect pests.
The most common pests that love to infest broccoli plants include:
- Cabbage moths
- Diamondback moths
- Flea Beetles
Here’s a quick rundown of these three common pests, the type of damage they cause, and how you can prevent them from feasting on your lovely broccoli plants.
Cabbage moths are the number one enemy of a broccoli plant. Have you noticed large white moths fluttering around the leaves of your broccoli?
Maybe you thought they were pretty, and that your garden was finally getting some beneficial pollinators.
In reality, the white moths may be pretty, but they are not beneficial pollinators.
Actually, they’re not even moths.
They’re technically butterflies, and they’re fluttering around like that because they’re laying eggs underneath the leaves of your otherwise healthy broccoli plant—about 300 to 400 eggs, to be exact.
Their eggs are tiny and will eventually hatch green caterpillars that grow big and fat off your nutritious broccoli. They feed voraciously on the inner and outer leaves and will devour the actual florets and broccoli heads, too.
The “ol’ faithful” method of preventing insect infestations is the (slightly gruesome yet undeniably effective) pick-and-squish technique.
Handpick the ones you can see and then squish them or put them in a bucket of soapy water. If you only have a few plants, this is a great option.
If you have a large crop, you’ll be better off using an insecticide. An effective and organic choice is Bt (Bacillus thuringiensis).
It’s a naturally-occurring bacteria that will effectively kill cabbage moth caterpillars.
If you don’t want to spend the time squishing bugs or spraying every week, try using row covers. This method requires the least amount of effort and will prevent the moths from laying eggs.
Flea beetles are very easy to identify because they leave multiple small holes in leaves that look like they were caused by buckshot.
You can control flea beetles, but if they infest in large numbers on a young plant, they will cause premature death.
You can identify these pests because they’re aptly named: they look like a cross between a small black beetle and a flea.
They also jump like fleas too, which renders the traditional pick-and-squish method ineffective.
Severe damage from these pesky beetles will cause stunted growth and the inability to flower or fruit. Essentially, they will kill your broccoli if their population is left unchecked.
Flea beetles overwinter in the ground and love rotted plant debris, so clean your garden well when the seasons over. You can try planting broccoli seeds or seedlings in sterilized soil for extra protection.
Or, try using floating row covers as a barrier, particularly on young plants that are more vulnerable.
You can also try using trap crops as a sacrificial offering to prevent your actual crop from sustaining damage. Use other Cole plants like brussels or cabbage.
Another method is to put down thick mulch to prevent them from reaching the surface or use diatomaceous earth or even neem oil to prevent infestations. Other insecticides work but will need frequent reapplication.
For a more natural method, make a mixture of two cups of rubbing alcohol, one tablespoon liquid soap (Dawn is acceptable), and five cups of water.
Use this mixture to spray your plants or dust them with talcum powder.
Another method is to plant trap crops, particularly marigolds. Just like with cabbage moths, you can also use row covers to provide a physical barrier between your plants and the annoying pests that love to feed on them, like flea beetles.
The freshly hatched diamondback moth larvae will devour the entire leaf (but not the ribs) of your broccoli plant, both upper and lower.
When they’re mature, they leave large, ragged holes with irregular edges on the undersides of the leaves.
The larvae can be green when young and then turn brown once they mature.
The mature larvae will actually drop from the leaf on a silken line (like a spider) if you disturb them, making identification simple.
An existing infestation can be treated with Bt. Apply this organic insecticide in the late afternoon or early evening to avoid the sun’s UV rays breaking down the bacteria.
If you want an even more natural method, try getting parasitic stingless wasps (Cotesia plutellae, Diadegma insulare, and Microplitis plutellae are commercially available).
These will use the diamondback moth larvae as a host and kill them.
It’s a great way to prevent an infestation without the use of an insecticide. However, you can use a broad-spectrum insecticide.
Remember, this method is effective, but it will also cause beneficial insects or pollinators to die. So, use sparingly.
Broccoli: the bane of six-year-old children everywhere that don’t want to finish their dinner before they have dessert.
While your younger self may have made broccoli your enemy, your older self most likely finds it delicious.
If you’re growing broccoli and discover your leaves have suddenly developed raggedy holes, you’ve got an insect problem,
The most common culprit is the cabbage moth. Okay, cabbage butterfly. They love broccoli and will lay hundreds of eggs on the undersides of leaves.
Or, you could be suffering from some other common pests like flea beetles or diamondback moths.
To get rid of these pests, try handpicking, row covers, or an insecticide. Using the natural bacteria Bt is an excellent choice.
It’s also more natural and less harmful to beneficial insects and pollinators than a broad-spectrum insecticide.
With these methods, you’ll be enjoying delicious broccoli florets all summer and never have to worry about heading out to your garden and finding holes in your leaves again.
Taking care of houseplants and gardening are my greatest passions. I am transforming my apartment into an urban jungle and am growing veggies in my indoor and outdoor garden year-round.