Resistant Varieties May Help - Market Prize cabbage may have some resistance to the imported cabbageworm, but not to the cabbage looper, in comparison to Abbott & Cobb #5, Green Winter, and Rioverdi which do exhibit some resistance. Red cabbages, like Red Danish, Mammoth Red Rock and Red Acre are less attractive to the cabbage looper moth than green cultivars, so fewer eggs are laid on them, resulting in fewer hungry loopers.
Planting Date - Plant early, or plant a fall crop only. You can sidestep much of a cabbage looper's threat simply by not sowing or transplanting the target plants during the cabbage looper peaks. Stagger your planting dates. Start some seedlings early indoors and set them out at normal planting time. If the plants are big enough they will not be hurt so much by some damage. Sow small groups of plants a week or 10 days apart so your plants won't all be at the most vulnerable stage at the same time.
Predator Birds And Other Animals - Baltimore orioles, bluebirds, chickadees, robins, sparrows, starlings, redwing blackbirds, cowbirds, and flickers, as well as toads and skunks, all like to eat cabbage loopers.
Predator Insects Found In Garden - The following beneficial insects are commonly found in and around healthy, well-balanced gardens in many parts of the country. See page xxx for more information about each one.
If you find cabbage loopers that have turned chalky white and appear nearly dead they have likely been infected with NPV, or nuclear polyhedrosis virus. They might be lying motionless on top of leaves or even hanging from the underside of a leaf. Leave the carcasses where they lie so the virus can work on additional loopers.