Cabbage White Butterfly UK

Cabbage white caterpillars can strip brassica plants to bare stems in days. Netting is the only truly reliable defence.

Pest control advice verified against RHS guidance by the SoilCommander Growing Team.

Two Species

The UK has two cabbage white species. The Large White (Pieris brassicae) lays clusters of yellow eggs on leaf undersides; its gregarious caterpillars feed in groups and do severe damage. The Small White (Pieris rapae) lays single eggs; solitary green caterpillars are harder to spot and can be more damaging overall.

Peak Season

Adults are active from April to October with peak egg-laying in two main waves: late spring (May–June) and late summer (August–September). The second generation in August is typically the most damaging.

Control Methods

Fine mesh netting (1.3mm or finer): the only fully reliable prevention; fit immediately after transplanting and keep in place April–October
Inspect weekly: check leaf undersides for egg clusters and caterpillars; remove by hand
Companion planting: nasturtiums act as a trap crop, attracting egg-laying away from brassicas
Biological control: Bacillus thuringiensis (Bt) spray kills caterpillars without harming other insects
Encourage predators: wasps, blue tits, and robins all eat cabbage white caterpillars

Common Mistakes to Avoid

Letting netting touch the plants. The RHS warns butterflies can lay eggs straight through mesh at any point where it touches the foliage — keep netting held clear on hoops.
Assuming a quick visual check catches everything. Small White eggs are laid singly and easy to miss, unlike the Large White's obvious yellow clusters — a page can look clean and still carry solitary caterpillars.
Relaxing vigilance after the first wave. The second egg-laying wave in August–September is typically the most damaging of the two — don't remove netting or stop checking once the May–June wave has passed.

Frequently Asked Questions

Do I need to net brassicas all summer?

Yes — adults are active April to October with two egg-laying peaks (May–June and August–September), and the second wave is usually the more damaging of the two.

Which cabbage white species does more damage?

The Small White can be more damaging overall, even though its solitary caterpillars are far harder to spot than the Large White's obvious yellow egg clusters and gregarious feeding groups.

Can netting fail even when it's in place?

Yes, if it touches the plants — the RHS notes butterflies can lay eggs straight through mesh at any contact point, so keep netting held clear of the foliage.

Get the UK Garden Planner →

See all pest and disease guides: Garden Problems UK · Growing brassicas? See Cabbage, Kale and Brussels Sprouts growing guides · Browse sowing dates in the UK vegetable planting calendar

Last updated 4 July 2026

SoilCommander Editorial Team

UK vegetable growing guides · Checked against RHS & Met Office guidance

Every SoilCommander guide is written and maintained by our editorial team for real UK growing conditions, and reviewed against Royal Horticultural Society growing advice and Met Office climate data before publication.

Relevant next steps

Fix The Cause, Then Plan The Next Crop

Troubleshooting works best when you improve the growing conditions and record what changed for the next season.

Soil and plant careImprove the growing conditions behind many common plant problems. Hand tools for cleanupRemove affected growth, tidy beds, and keep problem areas manageable. Garden planner recordsNote what happened so you can rotate crops and avoid repeat issues.

Plan the next step

Use the printable UK Vegetable Garden Planner to turn this guide into sowing dates, bed layouts, and weekly garden tasks.

Get Planner

Cabbage White Butterfly UK | Protect Your Brassicas