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The Cabbage White Butterfly (Pieris rapae), which is also known as the Cabbage Butterfly, Cabbage White or Small Cabbage White is native to Europe, Asia, and North Africa, but is now widely found throughout North America, New Zealand, and Australia.
Cabbage White Butterflies are instantly recognizable to most gardeners thanks to their distinctive white wings with black bodies and small black dots on their wings. When in caterpillar form, Cabbage White Butterflies can usually be found on the undersides of leaves where they are less visible to predators.
What Are The Symptoms Of Cabbage White Butterflies?
The damage caused to brassicas by Cabbage White Butterflies is often instantly recognizable. The outer leaves of cabbages and cauliflowers will be riddled with holes. Kale and other leafy brassicas may be reduced to just stems.
Whilst it is usually just the outer leaves that are affected, occasionally caterpillars may burrow into the heart of the cabbage too.
Small, brown/green juicy droppings on the leaves of the brassicas are also a sure-fire sign Cabbage White caterpillars are present
What Do Cabbage White Butterflies Like To Eat?
The Cabbage White Butterflies’ natural food is members of the Brassicaceae family. For many of us, this means cabbages, kale, mustard, cauliflower, and Brussel sprouts.
Cabbage White Butterfly caterpillars are voracious eaters. From the moment they hatch from their tiny, yellow eggs, the caterpillars start eating. They will quickly turn a cabbage leaf into lace, and a large infestation can reduce a small brassica plant to just a stalk in a very short space of time.
It is estimated that in North America alone, Cabbage White Butterflies cause damage to crops costing hundreds of thousands of dollars each year.
Once the caterpillars have pupated and become butterflies they switch to drinking only nectar and cause no further damage to the plants.
Do Cabbage White Butterflies eat kale?
Cabbage White Butterfly caterpillars definitely eat kale. In fact, in my experience, kale is one of their favorite foods.
Do Cabbage White Butterflies eat lettuce?
I have never seen Cabbage White Butterflies, or rather their caterpillars, on my lettuces. I grow a lot of lettuce each year, and it tends to be the slugs and snails that are more likely to eat my lettuce leaves.
Do Cabbage White Butterflies eat spinach?
As with lettuce, I haven’t ever seen Cabbage White Butterfly caterpillars eating my spinach. I suspect the butterflies are attracted to brassicas by the smell, and spinach doesn’t smell anything like cabbage.
How To Control Cabbage White Butterflies?
When it comes to controlling Cabbage White Butterflies you essentially have 3 options, chemical control, biological control, or physical prevention.
I try to garden as organically as possible and I prefer to work with nature rather than against it but let’s look at the chemical control of Cabbage White Butterflies first.
Chemical Control Of Cabbage White Butterfly
There are a number of different chemical sprays available to treat Cabbage White butterflies. Most of them target the butterfly whilst it is in the caterpillar stage, so you will need to spray under the leaves to be most effective.
Remember, chemical sprays will often kill beneficial creatures as well as the Cabbage White Butterfly catterpillar.
Using pesticides and insecticides to kill Cabbage White caterpillars often results in killing Lady Beetles, hoverflies, and bees in the process.
Organic Cabbage White Butterfly Sprays
Every year more and more organic sprays to control pests come on to the market. Consumer demand is driving the trend toward organic. For a while now I have been using Monterey LG6332 Bacillus Thuringiensis (BT). This spray is approved for use in organic gardens and I have found it to be really effective. Bacillus Thuringiensis is often just referred to as BT.
BT works by blocking the caterpillar’s digestive system. After being sprayed, the caterpillars stop eating and within 2 or 3 days die from starvation. BT is said to have a minimal negative impact on the ecosystem and is said to be harmless to most other species of insects.
Homemade Cabbage White Butterfly Sprays
A large number of homesteaders make their own sprays to control caterpillars. Whilst caution should always be exercised when making homemade concoctions, there are many recipes for homemade brews on the internet.
I have had good luck mixing 2 tablespoons of vegetable oil-based liquid soap with 1 gallon of water. This liquid should be sprayed on the plants directly, either first thing in the morning or late in the evening, taking care to coat all the parts of the plants where the caterpillars or the eggs might be, including the undersides of the leaves.
Other homemade sprays use garlic as the main ingredient. Some use chilis and others use neem oil. In my experience, some of these homemade sprays work for some people and not for others.
One unusual twist on the homemade Cabbage White Butterfly control comes from Terry Walton of BBC Radio 2 who sprays his cabbages with a stinky mixture made by letting rhubarb leaves rot down in a barrel of water. Terry claims this spray smells so bad it confuses the Butterflies and they don’t lay their eggs on the brassicas in the first place.
Physical Barriers To Prevent Cabbage White Butterfly
One of the most effective ways to deal with Cabbage White Butterflies is by way of a physical barrier. Covering your brassicas with horticultural fleece will prevent the butterflies from getting to your brassicas in the first place, meaning they can’t lay their eggs and you won’t end up with any caterpillars.
In the past, I have made long tunnels covered in horticultural fleece which I placed over rows of cabbages or kale. I have also made individual wigwams that could be placed over the plants.
Essentially, it doesn’t matter what your design is, providing the barrier completely covers the plants. If there are even the smallest of gaps the butterflies will find a way in.
If you have a small number of seedlings you need to cover, placing a 2-liter drinks bottle with the bottom cut off over the plant will prevent the butterflies from getting to the plants, and act as a mini-greenhouse, give the seedling a little extra warmth.