Cabbage Worms

Pieris rapae and Trichoplusia ni

Insectalso: Imported cabbageworm, Cabbage looper, Cabbage white caterpillar, Cabbage moths, Cabbage moth

The green caterpillars that chew ragged holes in cabbage, kale, broccoli, and their kin and tunnel into the heads. Several species feed together; the velvety imported cabbageworm and the looping cabbage looper are the most common.

🔎 How to spot it

The imported cabbageworm is velvety green with a faint yellow stripe and creeps along on stubby legs; its adult is the white cabbage butterfly you see fluttering over the garden. The cabbage looper is smooth green with thin white side stripes and arches its body like an inchworm as it crawls. Both reach about an inch. Look for large ragged holes, caterpillars resting along the leaf midribs, and dark green fecal pellets.

🥀 Damage it causes

The caterpillars chew large, irregular holes in leaves, bore into broccoli and cabbage heads, and foul the harvest with greenish-brown droppings. Seedlings can be stripped, and contamination of the part you eat is often the bigger problem on mature plants.

🛡️ Prevent it

Float row cover over cole crops from transplanting to keep the egg-laying butterflies and moths off; seal the edges and leave it on, since these crops do not need insect pollination. Scout the leaf undersides for the bullet-shaped eggs and young caterpillars, and clear out old brassica debris that harbors them.

🧯 If it is already here

Handpick caterpillars and rub out the egg clusters; on a few plants this keeps up with them. The organic spray Bacillus thuringiensis (Bt) is very effective, especially on young caterpillars under a quarter inch, but it breaks down in sunlight, so apply late in the day and reapply after rain. Spinosad is another low-impact option.

💡 Good to know

Bt works best caught early, so scout often and spray while the caterpillars are small. The white butterflies are the easiest early warning: when you see them patrolling the bed, eggs and caterpillars are not far behind. Several caterpillars (imported cabbageworm, cabbage looper, diamondback moth) often feed together and are managed the same way.

🌱 Plants it attacks

56 plants in the library can be attacked by this pest

For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.