Garden Pest / Gardening / Self Sufficiency / In The Garden

{Garden Pest} Cabbage Moth/Butterfly

The evil cabbage moth. Image from Yates.

A few weeks ago I was feeling pretty good about my brassicas and their infiltration (or lack thereof) by the cabbage moth (also known as the cabbage butterfly or pieris rapae) . I’d seen a few flitting around the garden, but hadn’t spotted any landing on my plants, and I thought that my companion planting with onions had done the trick.

Even during the heat wave I didn’t really notice anything wrong, and thought that they were going marvelously, given the temperatures.

That was last week.

This week I got out of my car and wandered past the vegie patch. And wondered what on earth was going on with the horribly decimated plants that were hanging out there.


My first thought was snails (those pesky beasts) but I haven’t really seen many around the garden lately, and it certainly hasn’t been wet enough for them to be out in their droves.

So I got closer. And found the culprit.


My first thought was something along the line of “ewww gross” and my second was “how do I get rid of cabbage moth caterpillars?”.

Turns out someone else in the garden was working on the answer to that question for me.



The elusive ladybug. I never see hide nor hair of them when my roses are covered in aphids, but apparently they are quite happy to dine on cabbage moth eggs.

Google informs me that they predate on cabbage moth eggs, but it doesn’t tell me how effective they are. With that in mind I took to chopping off the leaves which seemed most covered by eggs (but I left some for the ladybugs to dine on. I’m not sure if I’m going to regret that or not).

I also went in search of the caterpillars. They’re simultaneously really tricky and really easy to spot. A cursory glance won’t reveal them, but once you know what you’re looking for they seem to be everywhere! I think I killed (or picked off and threw away) about 30 caterpillars. I’m hoping that when I go out and check on the plants tomorrow there aren’t more of them.

Once eggs and caterpillars have struck there’s a limited number of things you can do: you can try removing the eggs/caterpillars by hand and destroying them, encouraging natural predators (such as birds and ladybugs), spraying with a sour milk or garlic solution or spraying with a commercial spray that contains Bacillus thuringiensis (BT). This is supposed to target only caterpillars, and be safe for other insects (like bees and ladybugs).

Alternatively you can try preventing the moths from landing and laying in the first place. There’s a few ways to do this: catch and destroy any cabbage moths in the garden, establishing an insect-proof netting around plants (though this may also stop beneficial insects), spacing out plantings to make it harder for the cabbage moth to identify and land on the brassicas. Some people also plant ‘sacrificial’ plants, like nasturtiums, which also attract the cabbage moth. They let them land on/lay on this plant in order to keep them off their brassicas.

On the plus side I’m not planning on eating the brassica leaves so it’s not as though the plants are doomed, but I suspect they might need a fair few number of leaves for that whole photosynthesis thing…

Have you been affected by the cabbage moth? How do you deal with it?

7 thoughts on “{Garden Pest} Cabbage Moth/Butterfly

  1. The cabbage moth is going to flutter into your garden. There is no question about that. I spray my seedlings with Bt before setting them out, and continue to spray with Bt or a light lemon soap mixture until harvest. By so doing, I can use a really light mixture. If I do see ladybugs, I back off a little with the spraying. But I am going to hit the follow-up comments to see what other people say.

    • They certainly do flutter in! I was hoping they wouldn’t manage to spot the brassicas, though. Here’s hoping the plants manage to survive the caterpillar attack and last til Winter!

  2. Now you have me thinking! I am trying to think what I call them, but I THINK it is “Cabbage White”, and I never add “butterfly” or “moth” to the name. Maybe “Cabbage Butterfly”? These are clearly a butterfly (clubbed, not feathered antennae), not a moth.

    I see the great Wikkipedia says they are called moths in the USA – that’d be right. 😦

    But they are still bastards! Them, and aphids, are the reason I do not grow Brussels Sprouts. I LOVE Brussels Sprouts.

    Go Ladybugs!

    • They’re certainly butterflies, but for some reason I always grew up knowing them as “cabbage moths”. No idea why!

      I haven’t tried growing brussel sprouts, but I’ve been tempted to. I’m toying with getting some garden netting for the brassica section, but not sure I can be bothered sectioning the plants out. I might just keep trying with the companion planting/spacing the plants out.

      If I do manage to find a secret formula for success I’ll be sure to let you know!

    • Trust those pesky caterpillars to all turn up when it was ridiculously hot so I wasn’t spending as long in the garden keeping an eye on it!
      Now that it’s cooled back down I’ll have to go back to watching those sneaky pests VERY carefully!

  3. Pingback: See How My Garden Grows: February 2014 | on the ning nang nong

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