How to Control Cabbage Worms in Your Vegetable Garden
If you see white butterflies near your broccoli or kale, beware: Their larvae (green caterpillars called cabbage worms) love to munch on all parts of brassicas, from the stems and leaves to the flowering buds. They are technically known as the imported cabbage worm, since they're native to Europe—but today, you can find them all across North America, where they reproduce frequently over the course of a single growing season (which is bad news for your garden). If you want to ensure the success of your vegetable beds, you'll need to find a way to thwart them.
Luckily, this isn't difficult. To manage cabbage worms, intersperse flowering herbs like dill, fennel, and cilantro in your beds, suggests Jessica Walliser, the author of Attracting Beneficial Bugs to Your Garden ($6.12, amazon.com). The reason? They will lure insects like assassin bugs and spiders, which will swoop in and devour the bad guys.
Though planting flowering herbs is a solid preventative measure, you'll also want to check in on your brassicas frequently during their lifecycle to ensure that worms haven't joined the party, says Walliser. As they grow, check for the worms on the undersides of leaves, and pick off any that you uncover. Remember, these "worms" aren't worms at all—they're caterpillars that often blend in with the leaves they munch on (so check carefully!).
As for how to distinguish cabbage worms from other, less invasive caterpillars? Look for their telltale yellow stripe. Although, if you see any type of caterpillar on your broccoli or kale leaves, it's in your best interest to pull them off, notes Walliser—there are a myriad of species that feed on the very same plants.