Got Holes in Your Leafy Greens? You Have Cabbage Worms

Learn how to use organic solutions to protect your leafy green garden plants from damaging cabbage worms.

Cabbage worm damage

Have the leafy greens in your garden ever looked like this, with tiny holes eaten out of the leaves? A few weeks ago, I was greeted by this sight in my vegetable garden. Almost all of my lettuce plants had small holes eaten out of them. In addition, the leaves of my broccoli, cauliflower and kale had the same problem. New at vegetable gardening? Try these easy-to-grow vegetables.

These small holes are telltale signs of the cabbage worm. Actually, the are several insects that cause this type of damage and are generally referred to as ‘cabbage worms’. This includes the imported cabbage worm, the diamondback caterpillar and cabbage looper. The cabbage worm will eventually become a butterfly, while the diamondback caterpillar and cabbage looper will become moths.

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The adults come and lay their eggs on the leaves of cabbage, leaf lettuce, broccoli, cauliflower and kale and other leafy greens. The eggs quickly hatch and the young caterpillars start feeding. They are usually more prevalent in late summer and fall then in the spring. So, what can you do if you are seeing small holes on your leafy greens?

Solutions for Cabbage Worms

The best thing to do is to prevent the problem from happening in the first place by covering your leafy greens once sown or planted from transplants using a floating cover. But, since I already have an infestation, I need to resort to other methods.

  • Spraying leaves with BT (Bacillus thuringiensis) will work and is an organic solution.
  • Plant resistant varieties such as red-colored leafy greens, which the cabbage worm tend to avoid.
  • Introduce natural predators of the cabbage worm such as larvae of Trichogramma wasps, which devour the eggs before they hatch.
  • Plant your leafy greens in spring, rather than in late summer/fall when the cabbage worm is not as active.
  • Sprinkle diamotacious earth on and around each plant, which is a powder made up of the tiny, fossilized remains of aquatic organisms.  These tiny fossils have sharp edges that puncture the outer skin of insects, which leads to their death.  This is also an organic solution.

diamotacious earthDan Garber

So, which solution did I choose for my vegetable garden? I filled a unused spice jar with wide holes with the diamotacious earth and sprinkled it over and around my leafy greens.

diamotacious earth and leafy greens

Wash off your leafy greens before eating, which will get rid of any remaining traces of the diamotacious earth. I like to use organic solutions whenever possible when I garden. But, next year, I plan to use floating covers to keep them from laying eggs in the first place. Check out more options to try to keep caterpillars from bothering your leafy greens.

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Noelle Johnson
Noelle Johnson is a horticulturist and certified arborist who lives and gardens in the desert Southwest. When she is not writing or helping other people with their gardens, you can find her growing fruits and vegetables, and planting flowering shrubs and maybe a cactus or two.