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All it Takes is One

June 13, 2011

One parent pest landing on one food crop start can lead to disaster. Even well protected crops can still be at risk. But, with regular monitoring, it is possible to save even an infested crop before the pests win out. And, you still won’t need a bottle of poison.

Notorious & Uninvited "Cabbage Worm" Enjoying Broccoli

Notorious & Uninvited “Cabbage Worm” Enjoying Broccoli

This weekend I noticed some damage on my brassica crops — broccoli, dino kale and purple cabbage. I knew right away that despite my best efforts to protect these plants, somehow a pesky cabbage butterfly momma had gotten to them. And, she laid her eggs. And, they hatched. And, the baby caterpillars were eating my crops!

All it takes is one. One day when the greenhouse is venting, and a butterfly gets in. One hot afternoon when the cold frame where they’re hardening off is cracked to cool, and a butterfly gets in one. One day when the plastic hoop house blows open, and a butterfly gets in. That’s all it takes. She lands. She lays and egg, and she’s off. And, what’s really unfortunate? These white butterflies (not moths) hatch and fly in cool, moist temperatures (as well as hot ones), so they’re out earlier than many other flying insects looking for their favorite cool season crops like cabbage on which to lay their eggs.

So, what happens when you’re got cabbage caterpillars? Well, they eat your crops, and they chow them down fast. They eat with chewing mouth parts, so the damage looks like a chewing. They poop blackish-green all over the interior of of the plant, if they haven’t eaten that part first and really killed the plant. Those are the signs; look for them. Often they’re much easier to see than the the green caterpillar itself.

These caterpillars are quite well camouflaged for most brassica crops. They’re a bright green worm that tends to blend very well with their favored food crops. A large portion of the brassicas are tones of grey-greens that allow these little wormy critters to blend into. Think broccoli, Brussels sprouts, kale, cabbage, and the like.

Webbing & Damage Left Behind after Metamorphosis

Webbing & Damage Left Behind after Metamorphosis

If you see the signs, guaranteed you’ve got the pest. Start by looking at the interior of the plant and along the up-side mid-rib of each leaf. Those are their favored spots when at rest. If you don’t find a caterpillar on one plant, move to the next, and you may find it there. If you happen to find a cottony looking casing, that’s likely the caterpillar getting ready to metamorphosis into another of the white butterfly parents that will be flittering about the garden.

So, what to do when you find one of these worms? Well, if you’ve got a kid with a butterfly cage, go ahead and collect a leaf and a caterpillar. Watch it finish its life cycle. Then kill the butterfly. Yeah, sounds cruel, right? If you don’t, that butterfly will kill your crops…or your neighbor’s crops. Really, I’d skip the whole “watch it grow up” thing and just advocate for squishing each green, creepy crawler as you find them.

Bright Green Worm on Purple Cabbage - Ready for Squishing!

Bright Green Worm on Purple Cabbage – Ready for Squishing!

And, if you find one caterpillar, odds are momma laid several eggs, so check your crops every day over the course of several days until you are certain that you’ve gotten rid of all of them. Odds are, if your crops have been well protected, it was just one day when the butterfly laid her babies in your veggie garden. So, within a few days all of her progeny should have hatched and, under your careful watch, been dispatched with a quick pinch between the fingers. Guaranteed you’ll have a green thumb after this kind of work!

Too, usually, I try to cut out the most damaged outer leaves on my crops, so I can easily keep track of the signs of new damage. (This isn’t always possible if you find the problem after a lot of damage has been done; if you remove too much living material from your crop, you may take away its ability to rejuvenate. This is a balancing act!)

Now, if your cabbage is purple like mine, these suckers just can’t hide. They stand out & are really easy to see and kill quickly. Just pinch’m and let their juicy guts mingle with the soil where hopefully they’ll give back some of those nutrients they’d drawn from the plant above.


  1. […] and insect larvae too. On occasion, you’ll even see these small birds in hot pursuit of pesky cabbage butterfly flitting through the garden. And although starlings may seems a loud nuisance, they will aerate […]

  2. […] of the worst pests on our property has struck again. No, it’s not the cabbage worms or the root weevils or leaf miners. They’ll show up later. For now, it’s all happening […]

  3. […] in Richmond, Virginia. And, if you’ve seen these flying around in your garden, be sure to read more in our earlier post that shows photos of their caterpillar phase and the damage those green, wormy creatures do so very […]

  4. Carmen says:

    I had to pull on my brussels sprouts and collards earlier this Spring, but I found out later that, Bt with kurstaki works best for Cabbage worms/loopers… (brand mention by writer removed by blog editor)…I will sow again for Autumn garden.

  5. Carmen, we definitely prefer to avoid using any pesticides to deter these pests. Horticultural fleece and crop monitoring work great!

  6. We’re a group of volunteers and starting a brand new scheme in our community.
    Your site offered us with valuable information to work on. You have done a formidable task and our entire community will be thankful to you.

  7. […] of the worst pests on our property has struck again. No, it’s not the cabbage worms or the root weevils or leaf miners. They’ll show up later. For now, it’s all happening […]

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