Box Moth Caterpillars, also known as box tree caterpillars, can strip leaves from your box plants or hedge.
Your plant may die in extreme situations.
Many of us have box topiaries or hedges in our gardens. This can be a real problem.
This pest is relatively new. It arrived in the UK via Europe and Asia in 2007. It’s spreading quickly around the globe to places like the USA, Canada, and others.
I found box moths on my topiary this year. This included my favorite topiary spiral. This is my most expensive plant and focal point in the garden.
The box topiary spirals at a happier time.
Box moth caterpillar damage: How to identify it
Box tree caterpillars start causing damage in the spring when they appear. They usually spend the winter in your box plant, wrapped up in their silk web.
You will notice that the new growth of your plants is a darker green, or even a brown-gray color, depending on whether it was damaged by grubs.
You will notice a white or silvery net with dying leaves and then the caterpillar.
You can find these patches by looking at the top photo. If you look closely, you’ll see that these patches have dead or dying foliage. In the lower picture, you can see a bigger patch.
What does a box moth caterpillar look like?
Box moth caterpillars are striped in black and citrus green. The caterpillars have blackheads, and the fine web that surrounds them protects them.
Box tree moth caterpillar
What is the main food of box moth caterpillars
All of us are encouraged to create wildlife-friendly gardens so that predators will eat our pests. This makes gardening easier and is better for our environment.
Helen Bostock is Senior Wildlife Advisor at the RHS. We spoke about gardening to promote biodiversity. She explained how slugs, snails, and other critters help compost piles to work better.
Birds and ladybirds will eat the majority of your aphids. As long as you are willing to accept some nibbled-off leaves, you can let nature take its course.
No one suggests that you do the same for box moths. They are not currently being preyed upon by natural predators because they have only recently arrived in the UK. Early reports in the UK indicate that starlings, sparrows, and bluetits are beginning to feed upon them, but in insufficient numbers to stop the spread.
Asian hornets in Asia eat caterpillars of box moths. However, importing them to the United States would create other problems.
Box moth caterpillars: How to eliminate them
You can use nematodes to kill box moths. Nematodes are available ( Nemasys fruit & veg, a popular brand) for this purpose. Please note that Amazon links are affiliate links. See disclosure.
It is important to carefully read and follow the instructions for nematodes. For example, you can’t store them for very long and may need to store them in the refrigerator.
It is possible to use a product named Top Buxus that has been used by many professional gardeners around the globe. It is safe for birds and bees.
It is a bacterial pesticide with an active component based on Bacillus Thoringiensis Subs Azawai. It’s not licensed yet for use in the UK. However, it is licensed both for amateur and professional uses in other countries. It depends on your location as to whether you can buy it.
Search online for ‘box moth professional treatment.’ Verify that the products used are those that cause minimal damage to wildlife or other insects.
Insecticides that work against multiple pest types will likely also disrupt the natural balance between pests and predators. Avoid all-purpose sprays as much as possible. Use it only on a dry, still day to avoid the spray drifting.
Repeat any treatment you’ve had several times over the course of the summer.
Box plants should be pruned and fed
Many professional gardeners have told me that if you clip the box, then you will be cutting off some caterpillars (or dividing them in half). It’s not a cure but a good way to reduce the number.
We’ll then clip our box topiary. Never leave clippings lying around or in a compost pile.
It was also suggested that I feed the plants. This is not a cure but it will help the plants to recover quicker and minimize the damage.
Plants that are well-established and healthy will always be able to withstand pests, diseases, and other problems better than those plants in need of care or newly planted plants.
What other plants do box moth caterpillars consume?
They don’t. It’s not the caterpillar of the box tree moth.
Don’t ever plant box plants
Unfortunately, the only way to avoid both box moths and box blights is to stop growing the box.
In the future, there may be a blight-resistant box variety. Treatments like TopBuxus Xentari are also likely to be licensed more widely.
It’s a shame because the box is a great plant, particularly for the topiary. In the gardening community, there has been much debate about which are the best alternatives to the box. Ilex crenata is the most similar-looking plant to box. However, it has not performed well.
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