How to Identify Cabbage Worms
Cabbage worms are velvety green larvae. They have a few faint yellow stripes. They are not to be confused with cabbage loopers, which are yellow-green caterpillars. Unlike cabbageworms, cabbage loopers raise and lower their bodies as they move because they have no middle legs. Cabbage worms become cabbage white butterflies, which are mostly white with a few black markings. Cabbage white butterflies might seem like a pretty addition to the garden, but they are probably laying eggs on the undersides of leaves.
Where you find cabbage worms and cabbage loopers, you also might find the eggs and larvae of the diamondback moth and the zebra caterpillar. The camouflage of these creatures is excellent, so you will often see the frass, or fecal matter, that they leave behind before you see them.
Photo Credit: Cabbageworm eggs like the one in this picture are absolutely tiny, so you might not see them before it’s too late.
Cabbage Worm Damage
Cabbage worms can happily eat away at the bases of cabbage, cauliflower, or the heads of broccoli without being noticed. They feed on foliage, and eventually they can leave plants only with stems and large veins. If left to their own devices, cabbage worms can devour your crops. Their fecal matter can also stain and contaminate the produce.
Photo Credit: Purdue University. Imported cabbageworms feed on the flesh of foliage and often hide on the undersides of leaves.