🐛 Cabbage Worm
Pieris rapae
A pretty white butterfly with a day job destroying your brassicas.
How to identify
Velvety green caterpillar about an inch long with a faint yellow stripe down its back — blends perfectly into cabbage leaves, so look twice. The adult is the small white butterfly fluttering around your garden laying the next generation one egg at a time.
Damage signs
Chews round holes in outer leaves and burrows into cabbage and broccoli heads, leaving green frass pellets behind. A few worms can render a whole head unmarketable and unappetizing.
Plants it attacks
Cabbage, broccoli, cauliflower, kale, collards, Brussels sprouts, radish, turnip
Non-chemical controls
- Floating row cover from day one — the number-one defense, because it blocks the butterfly from ever laying eggs.
- Handpick the green worms (check leaf undersides) and drown them in soapy water.
- Bt spray on foliage targets caterpillars specifically without harming pollinators.
- Plant nasturtiums as a trap crop nearby — the butterflies prefer laying on them, and you sacrifice the trap plants instead of your cabbage.
- Encourage paper wasps and parasitic wasps by planting small-flowered nectar sources like alyssum — they parasitize the caterpillars.
Nerdy fact: That 'cute' white butterfly was accidentally introduced from Europe in the 1860s and has been photobombing North American gardens ever since. It's one of the most successful invasive insects on the continent — all while looking innocent.