How to identify and manage cabbage white butterflies and caterpillars

UK seasonality and monitoring

Butterflies and caterpillars commonly appear from late spring through summer.

During this period inspect Cabbage, kale, broccoli, cauliflower and other brassicas, concentrating on the crop stage and plant parts described above. Note when and where fresh injury appears; old feeding marks can remain after the pest has moved on.

Crops and plants affected

The recorded hosts are Cabbage, kale, broccoli, cauliflower and other brassicas. This list identifies plants worth checking; it does not mean every crop is equally vulnerable. Start with the listed plants and inspect the tissue where this pest feeds.

Check affected crops for these signs: Holes and skeletonised leaves, sometimes heavy defoliation. Match the symptom to a live pest, larva, egg or characteristic feeding sign before deciding that treatment is needed.

Damage and likely consequences

Holes and skeletonised leaves, sometimes heavy defoliation. A small amount of old damage on a vigorous plant may be cosmetic. Continued feeding on roots, seedlings, growing points or edible parts can reduce establishment or yield.

On Cabbage, kale, broccoli, cauliflower and other brassicas, judge severity by checking whether injury is fresh and spreading, whether the plant is still growing, and whether the edible part is affected. Avoid removing a crop based on one ambiguous mark.

Prevention

Check the undersides of brassica leaves and the heart of the plant. Fine mesh works only when fitted before butterflies lay eggs and sealed at the edges.

Control and integrated management

Pick off eggs and caterpillars by hand, checking both leaf surfaces and the growing point rather than treating the whole bed.

Natural predators and wildlife-conscious choices

Share space with butterflies where damage is tolerable, but protect young crops when needed.

For cabbage white butterflies and caterpillars on Cabbage, kale, broccoli, cauliflower and other brassicas, use a barrier or hand removal only where it fits the crop and life stage. Keep any cover taut, inspect it for trapped wildlife, and remove it when protection is no longer needed.

Long-term management

Inspect brassicas through the caterpillar season and keep covers on while plants are vulnerable; remove them when the risk has passed.

For cabbage white butterflies and caterpillars on Cabbage, kale, broccoli, cauliflower and other brassicas, record the bed, crop stage and date when fresh damage first appears. Those notes help time protection and monitoring before the same crop stage is vulnerable next season.

Common mistakes

A symptom alone is not a diagnosis. Large white butterflies usually lay clusters of yellow eggs, while small whites lay single eggs. The caterpillars differ in colour and behaviour; inspect both sides of brassica leaves and the central growing point. Look for a matching live pest or fresh feeding sign before intervening.

A quick look at the top of the leaf can miss eggs and small caterpillars underneath or near the heart.

If damage continues

Recheck Cabbage, kale, broccoli, cauliflower and other brassicas where new injury is appearing, including the hidden feeding site: roots, folded leaves, leaf undersides, flowers or fruit as appropriate. If identification remains uncertain, photograph a live specimen alongside the damage and ask an allotment association or horticultural adviser.

If the recommended control (Remove eggs and caterpillars by hand; keep covers secured and inspect regularly.) has not helped, confirm that it was fitted or applied at the right crop stage and that fresh damage is still occurring. Old marks do not heal when the pest has gone.

Frequently asked questions