Cabbage Looper

A Comprehensive Guide to Identification, Damage, and Control

Cabbage looper (Trichoplusia ni) is a common pest that feeds on cabbage, broccoli, cauliflower, and other members of the brassica family. These caterpillars are called “loopers” because of their unique way of moving, which involves making an arch with their body and then stretching forward to create a loop.

Identification

The cabbage looper is a light green to yellowish-green caterpillar with a distinctive white stripe running down its back. They are about an inch in length and have three pairs of legs near the head and four pairs of prolegs on the abdomen. They also have a pair of fleshy protuberances called “scoli” on the last segment of their body. Adult moths are brownish-grey with a wingspan of about 1.5 inches.

Damage

Cabbage loopers feed on the leaves of plants, causing damage to the foliage. They chew holes in the leaves and can skeletonize the plant if the infestation is severe. They can also cause stunted growth and reduce the yield of crops.

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Natural Control Methods

  1. Handpicking: One of the simplest and most effective ways to control cabbage loopers is to handpick them off the plants. Check the plants regularly, especially the undersides of the leaves, and remove any caterpillars you find. Drop them into a bucket of soapy water to kill them.

  2. Beneficial Insects: Encouraging natural predators, such as parasitic wasps, can help to control cabbage looper populations. These insects lay their eggs on the caterpillars, and the developing wasp larvae feed on them, ultimately killing the caterpillar. You can attract beneficial insects to your garden by planting flowers, such as marigolds, alyssum, and dill.

  3. Crop Rotation: Cabbage loopers can overwinter in garden debris and soil, so crop rotation is essential to prevent their buildup in the soil. Rotate brassica crops with non-brassica crops to reduce the population of cabbage loopers.

  4. Neem Oil: Neem oil is an effective natural insecticide that can be used to control cabbage loopers. Mix 2 tablespoons of neem oil with 1 gallon of water and spray the solution on the plants, focusing on the undersides of the leaves where the caterpillars tend to feed. Neem oil is safe to use and does not harm beneficial insects.

  5. Bacillus Thuringiensis (BT): BT is a naturally occurring bacteria that produces a toxin that is toxic to cabbage loopers. BT is available as a liquid concentrate or powder, which can be sprayed onto the plants to control the caterpillars. The caterpillars will ingest the bacteria, and it will kill them within a few days.

  6. Sticky Traps: Sticky traps can be used to trap cabbage loopers. Hang yellow sticky traps in the garden to attract the moths. The moths will land on the traps, and the sticky surface will trap them, preventing them from laying eggs on your plants.

Conclusion

Cabbage loopers are a common pest that can cause damage to your garden, but there are many natural methods of control that you can use to manage their population. Handpicking, attracting beneficial insects, crop rotation, neem oil, BT, and sticky traps are all effective ways to control cabbage loopers without resorting to chemical pesticides. By using these natural methods, you can protect your garden and the environment while still enjoying a bountiful harvest.