How to Get Rid of Cabbage Loopers | Quick Guide on Organic Control

Cabbage loopers, or Trichoplusia ni, are potentially disastrous caterpillar-like insects named for the loop-like shape their bodies make when they crawl. They love cruciferous vegetables, particularly those in the brassica family, and can plague a garden for an entire season.

Luckily, implementing solutions in a timely manner can eradicate them before too much damage is done.

Symptoms of a cabbage looper infestation

Cabbage loopers leave pretty characteristic signs. Aside from sightings of the little green caterpillar itself, they make themselves known by chewing irregularly shaped holes in the leaves of your cruciferous vegetables. You will also see brown waste from their feasts on leaves, and severe infestations can render your plants incapable of growing at a healthy rate.

How to prevent cabbage loopers

In an ideal world, you’ll never have to wage a war against these destructive little loopers. There are several things you can do to better your chances of deterring them throughout the season.

1. Introduce the looper’s natural enemies: Because of their bright color and size, cabbage loopers are pretty easy prey for birds. Create a bird-friendly environment before the growing season is in swing by planting near trees, bushes, and other tall plants. Introducing birdfeeders in the yard around your garden are other ways to let birds know they’re welcome.
2. Use row covers: If your plants are tolerant to them, using row covers can make it harder for the mature cabbage looper moths to deposit eggs on your cruciferous crops.
3. Employ crop rotation: This is good practice in general, but it is especially important for deterring or preventing re-infestation by pests like cabbage loopers. The persistent pests are known to overwinter, so moving the food source far away lessens the chance of a continued problem.

How to combat cabbage loopers

Unfortunately, some degree of cabbage looper infestation is likely no matter what you do. If things get out of control, there are very effective organic and pesticide-based options available to reassert control over your garden.

Organic methods

Pick them off

If your problem is mild or you catch it early, simply pick the larvae off by hand and drown them in soapy water. The eggs can be brushed off and met with the same end.

Remove weeds and plant debris at the end of the season

Cabbage loopers will overwinter on plant debris, making re-infestation likely, so removing all plant debris at the end of the season helps lessen the chance of this happening.

Use BT spray

This sounds inorganic, but it’s au naturale—BT, or Bacillus thuringiensis, is a spray made from bacteria that kills cabbage loopers. Use the spray early in the infestation for the best results.

Inorganic methods

If organic control isn’t important to you or if the above methods have proven ineffective, insecticides are an option. There are two ways to go about this:

1. The home-grown route: You can make “insecticidal soap spray” using dish soap and water. Spray it on the plants and the loopers themselves to kill the pests.
2. The store-bought solution: These are conventional pesticides. Many are available to control cabbage loopers, so check the packaging to ensure efficacy on your specific plant and pest. Pesticides generally need to be applied several times throughout the season.