Cabbage white butterfly

How to identify cabbage white butterflies

The cabbage white butterfly is white with distinct black spots on the wings and is around 40mm across. The butterfly lays its eggs on the underside of leaves. The larvae of caterpillars hatch from the eggs and then feed on the leaves or fruit, so it’s the caterpillar of the cabbage white butterfly that is doing the damage.

The caterpillar has a blue-green smooth texture and will start eating the outer leaves first before moving to the heart of the vegetable. Plants impacted are cabbage, broccoli, Brussels sprouts, Chinese cabbage, celery, beetroot, rocket, and watercress. Symptoms are large holes in the outer leaves and bluey-green frass (droppings) on the inside of the leaf or in the heart of the cabbage.

How do you manage them?

Cabbage white butterflies love nasturtiums and will often seek these plants out to lay their eggs on, instead of the Brassicas. A few things you can try to help manage them include:

• Planting nasturtiums as a decoy and other herbs and flowers amongst your brassicas to attract their natural enemy, predatory wasps.

• Try tricking them with decoys such as fake moths and eggshells, the theory being they think they are already home to caterpillars and are too much competition for eggs.

• Laying fine netting as an exclusion to stop moths laying their eggs on the plants can help but crucial to get the timing right to avoid trapping the emerging moths inside the netting.

• Control by either picking off the caterpillars or spraying them whilst still on the outside of the leaf before they tunnel into the heart.

• If infested with holes, then spray your plants with Dipel, onto both sides of the foliage to salvage your plants.