What is eating holes in my kale and cabbage leaves?
Small round shot-holes suggest flea beetles; ragged large holes with frass (green droppings) point to cabbage worms or imported cabbageworm — check both sides of leaves to identify which you have.
Two very different insects cause holes in brassica leaves, and they require different responses. Flea beetles are tiny (1–2mm), shiny black or bronze beetles that jump when disturbed. Their feeding creates dozens of small, round 1–2mm holes, giving leaves a shot-hole appearance. Damage is worst on seedlings and young plants; established plants can usually outgrow flea beetle pressure without intervention.
Cabbage worms are the larva of the imported cabbageworm butterfly (Pieris rapae), a small white butterfly with black wingtip markings that you've likely seen fluttering around brassicas in spring and early summer. The caterpillars are pale green and blend remarkably well with the leaf. They feed from the leaf margins inward, leaving ragged holes and small green pellets of frass on the leaf surface and nearby soil. A single large caterpillar can consume a significant amount of leaf in a day.
For cabbage worms, Bt (Bacillus thuringiensis) is the most targeted option — it's a naturally occurring soil bacterium that produces a protein toxic to caterpillars but harmless to humans, birds, and most beneficial insects. Apply it to the undersides of leaves where caterpillars feed, and reapply after rain. Hand-picking works well if you check plants every 2–3 days. Row cover over young plants before the butterflies arrive prevents egg-laying entirely.
For flea beetles, row cover at transplanting is the most reliable prevention. Diatomaceous earth dusted on leaves can reduce feeding. Established plants beyond the seedling stage usually tolerate flea beetle damage without significant yield impact — the holes look alarming, but a healthy kale plant can lose 30% of early leaves without affecting later productivity.
- AphidSoft, clustered insects on new growth causing curled leaves and sticky honeydew.
- Cabbage LooperRagged holes in brassica leaves made by a pale green caterpillar that loops its body as it moves.
- Cabbage MaggotBrassica transplants wilting and dying as white maggots tunnel through roots at or below the soil line.
- Imported CabbagewormRagged holes in brassica leaves with pale green caterpillars and green frass nearby.
- Carrot Rust FlyRusty tunnels through carrot and parsnip roots made by small white maggots feeding inside the root.
- How do I deal with cabbage worms on my kale and other brassicas?Bt (Bacillus thuringiensis) spray applied to the leaf undersides is the most targeted control for cabbage worms — hand-picking and row cover are also effective without any spray at all.
- I have aphids on multiple plants — do I need to spray everything?Aphids tend to colonize plants under stress and naturally crash when beneficial insects find them — water sprays and patience are often more effective than pesticides.
- Something is cutting off my seedlings at the base overnight — what is it?Cutworms — fat gray or brown caterpillars that live in the soil and feed at night — cut young stems at or just below the soil surface, and a simple collar around each stem can stop them.