How to Stop Cabbage White Butterflies Damaging Your Brassicas
Finding holes in your cabbage, kale or broccoli leaves? Cabbage white caterpillars could be responsible. These common UK garden pests feed on brassicas and can cause serious damage when left unchecked.
The good news is that you can protect your crops without relying on chemical insecticides. The most reliable approach is to prevent butterflies from laying eggs in the first place, using properly fitted insect netting or butterfly netting.
Here's how to recognise cabbage white butterflies, check for eggs and caterpillars, and keep your vegetables protected.
What Are Cabbage White Butterflies?
There are two common species of cabbage white butterfly found in UK gardens:
- Large white butterfly (Pieris brassicae): Its caterpillars are yellowish-green with black markings and often feed together in groups.
- Small white butterfly (Pieris rapae): Its caterpillars are generally green and often feed individually, making them harder to spot.
The adult butterflies are white with dark markings on their wings. They visit flowers for nectar, but the females also lay eggs on plants that their caterpillars can eat.
Commonly affected crops include cabbage, kale, broccoli, cauliflower, Brussels sprouts, swedes and other brassicas.
How to Recognise Cabbage White Butterfly Damage
The caterpillars, rather than the adult butterflies, are responsible for the leaf damage.
Look for these signs:
- Small holes appearing in brassica leaves.
- Large, irregular holes or badly chewed leaf edges.
- Green or yellowish caterpillars on the leaves.
- Small dark droppings on leaves or around the growing point.
- Yellow eggs on the undersides of leaves.
Large infestations can strip substantial amounts of foliage from plants. Young brassicas are particularly vulnerable because they have fewer leaves to lose.
Check the Undersides of Leaves for Eggs
Catching an infestation early can make a big difference.
Female large white butterflies usually lay clusters of yellow eggs, while small white butterflies generally lay their eggs singly.
Inspect the undersides of brassica leaves regularly during the growing season, especially when you see white butterflies flying around your vegetable beds.
If you find eggs, remove them carefully by hand before they hatch. Check the whole plant, including the smaller inner leaves.
1. Protect Brassicas with Insect Netting
The best way to prevent cabbage white caterpillar damage is to stop adult butterflies reaching your plants to lay eggs.
Garden netting both butterfly and Veggiemesh insect netting create a physical barrier while allowing light, air and rain to reach your crops. Both are suitable for protecting brassicas against cabbage white butterflies and several other vegetable pests.
Shop Veggiemesh Insect Netting
How to Fit Insect Netting Properly
- Check your plants first. Remove any eggs or caterpillars already present.
- Cover crops early. Ideally, put the netting in place when you sow or plant out.
- Allow growing room. Use garden hoops or a suitable frame to keep the mesh clear of the leaves where practical.
- Secure every edge. Peg down or bury the edges so butterflies cannot enter underneath.
- Inspect regularly. Check for gaps, damage or trapped insects and make sure the plants have enough space as they grow.
If leaves press against a loose cover, butterflies may still be able to lay eggs through openings in some types of netting. Supporting the cover above the plants helps reduce this risk.
2. Choose the Right Butterfly Netting for Your Garden
Different protective covers suit different pest problems.
Soft Butterfly Netting
Butterfly netting is designed to exclude cabbage white butterflies and can also help keep birds away from vegetables. It is a practical choice when these larger pests are your main concern.
Standard Veggiemesh
Veggiemesh has a finer weave and protects against cabbage white butterflies as well as pests such as cabbage root fly and carrot fly.
Ultra-Fine Veggiemesh
For gardens troubled by smaller pests such as flea beetles or whitefly, ultra-fine insect mesh offers more targeted protection.
Whichever cover you choose, a secure fit without gaps is essential.
3. Remove Caterpillars by Hand
If caterpillars are already feeding on your plants, check the leaves carefully and remove any you find.
Look along the leaf veins, on the undersides of leaves and near the centre of cabbage plants.
Hand removal can be practical for a small vegetable patch, but it requires regular checking because new eggs may hatch over time.
Once the plants are free from visible pests, cover them to help prevent more butterflies laying eggs.
4. Use Garden Hoops to Keep Netting Off Your Plants
Garden hoops make it easier to protect a whole row or raised bed of brassicas.
They hold the netting above the leaves, create room for growth and make the cover easier to lift when you need to inspect or harvest your vegetables.
For taller crops such as Brussels sprouts, use a sufficiently high frame or vegetable cage.
Measure the width and height of your plants before choosing your cover, remembering to allow extra material for securing the edges.
The supports are not necessary, they just make life easier.
5. Keep Checking Plants Throughout the Growing Season
Cabbage white butterflies are generally active from spring into autumn, depending on the weather.
Do not assume that one early inspection is enough. Check your brassicas regularly, particularly during warmer periods when butterflies are active.
Inspect the netting after windy weather and make sure it has not become loose or damaged.
Can You Use Nematodes for Cabbage White Caterpillars?
Beneficial nematodes are used to control particular garden pests, including some soil-dwelling larvae.
However, you should not assume that a general-purpose nematode product will control cabbage white caterpillars feeding on leaves.
For cabbage white butterflies, correctly fitted insect netting and regular inspection are more appropriate first steps.
Frequently Asked Questions
When do cabbage white butterflies lay eggs in the UK?
They can lay eggs during the warmer growing season, generally from spring into early autumn. The timing varies with weather conditions and butterfly activity.
What plants do cabbage white butterflies attack?
Their caterpillars feed mainly on brassicas, including cabbage, kale, broccoli, cauliflower, Brussels sprouts and related crops.
Does butterfly netting stop cabbage white butterflies?
Yes, suitable butterfly netting can prevent adult butterflies reaching the plants when the cover is properly fitted and secured without gaps.
Should I cover cabbages all summer?
Keeping brassicas protected throughout the period when butterflies are active can help prevent repeated egg-laying. Check the cover regularly and allow enough room for the plants to grow.
Can cabbage plants recover after caterpillar damage?
Often they can, provided enough healthy foliage and the growing point remain intact. Recovery depends on the age of the plant and the severity of the damage.
Is Veggiemesh better than ordinary butterfly netting?
Both can help exclude cabbage white butterflies. Veggiemesh has a finer weave and is useful when you also want protection against other smaller vegetable pests.
Protect Your Brassicas Naturally with Gardening Naturally
Preventing cabbage white butterflies from laying eggs is usually easier than dealing with caterpillars after they have started feeding.
For the best protection, cover your brassicas early, secure the edges carefully and check plants regularly.
Explore our range of protective garden mesh: