Why Are There Holes in My Kale Leaves?

Kale is one of the most pest-attractive brassica crops in the garden — its large, textured leaves provide food and shelter for a range of insects and molluscs. Holes in the leaves can be caused by several different culprits, and identifying which pest is responsible makes control much more targeted and effective. The size, location and pattern of the holes are the key clues.

Caterpillars — large ragged holes, often on outer leaves

Large, irregular holes with ragged edges, found anywhere on the leaf, are typically caterpillar damage. On kale, the main culprits are the caterpillars of the large white butterfly (Pieris brassicae) and the small white butterfly. The large white lays yellow eggs in clusters on the underside of leaves; hatching caterpillars are yellow and black and highly visible. The small white's green caterpillars are much harder to spot against the leaf. Both can defoliate a plant quickly. Check the undersides of leaves regularly from late spring to autumn and remove eggs and caterpillars by hand. Fine insect mesh (enviromesh) over plants before butterflies begin laying is the most effective prevention.

Flea beetle — tiny round holes, seedlings and young plants

Tiny, round, 1–2mm holes scattered across the leaf surface — as if the leaf were peppered with a pin — are the classic damage pattern of flea beetles. These small, shiny black or bronze beetles jump when disturbed (hence the name) and are worst on young seedlings and transplants in warm, dry weather. Established kale plants usually tolerate flea beetle damage without serious harm, but seedlings can be destroyed. Insect mesh at seedling stage prevents damage. Regular watering in dry weather reduces flea beetle activity.

Slugs and snails — smooth-edged holes, often overnight

Slugs and snails create smooth-edged, irregular holes and work mainly at night or after rain. On kale they tend to target the young heart leaves and the area around the growing point, and on young plants they can eat the whole growing tip. A slime trail is the giveaway. Check under leaves and around the base of plants at night with a torch. Slug control methods — nematodes, ferric phosphate pellets, barriers — applied before the damage becomes severe are most effective.

Cabbage white fly and other insects

Smaller holes with a papery texture where the surface has been scraped rather than penetrated cleanly can indicate vine weevil or other surface-feeding insects. If none of the patterns above match, examine the plant at night and in early morning when the pest is most likely feeding and visible. Most kale holes are cosmetic — the leaf is perfectly edible even with some damage — and the plant compensates by producing more leaf from the centre.