Cabbage loopers are small green, striped worms which are known as trichoplusia ni.
These green worms attack lettuce plants and can be extremely damaging to the lettuce crop. Trichoplusia ni will also attack the many plants in the cabbage family. Those cabbage family plants which are susceptible to trichoplusia ni cabbage loopers include broccoli, brussels sprouts, cauliflower, chinese cabbage, collards, kale, kohlrabi and of course the common cabbage. Cabbage loopers are known as trichoplusia ni, and should not be confused with imported cabbage worms, pieris rapae. These two worms are often linked together under the common name cabbage worms, however it is very rare that pieris rapae attacks lettuce plants.