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Description Cabbage looper adults are mottled gray-brown moths with a silvery, V-shaped spot in the middle of each forewing. Their wingspan is 1½ inches. Because they fly late in the evening, you rarely see them. Their larvae are green caterpillars with pairs of wavy, white or light yellow lines down their backs and one line along each side.
Where they live Cabbage loopers are found throughout North America.
Their life cycle Adult moths emerge in May from their overwintering cocoons to lay eggs. The eggs hatch in 3 or 4 days and the larvae feed for 2 to 3 weeks. They pupate for up to 2 weeks in thin silk cocoons attached to the stems or undersides of leaves. Three or four generations of cabbage loopers may appear in a year, depending on where you live.
Plants they attack As you might expect, cabbage loopers attack mainly cabbage and cabbage-family plants. They'll also feed on beets, celery, lettuce, peas, spinach, tomatoes, and flowers, including carnations and nasturtiums.
Why they're a problem Cabbage looper caterpillars damage plants by chewing large holes in leaves. If you have lots of them, they can ruin whole plants. Larvae are most damaging during the last few days of their development.
Organic damage control
Handpick caterpillars several times a week and spray Bacillus thuringiensis var. kurstaki (BTK) as well.
Attract predatory and parasitic insects to the garden with pollen and nectar plants.
If you live in the North, start your cabbage indoors and put the plants out in the garden very early to avoid peak populations.
At the end of the season, bury spent cabbage plants to destroy cocoons before adults emerge in spring.
Many native parasites and predators attack cabbage loopers. Invite these helpers into your garden by planting flowers for them to feed on when loopers are not prevalent. Beneficial insects prefer tiny flowers like those that make up the large, flat umbels of parsley, dill, fennel, and coriander. Alyssum and tansy are also known to attract beneficials.
