How to Stop Caterpillars Eating Box Plants UK

Caterpillars can be a nuisance when they start eating box plants in the UK. Box plants are a popular choice for gardeners as they are versatile and low maintenance. However, caterpillars can quickly destroy the leaves and foliage of these plants. Fortunately, there are a few ways to stop caterpillars from eating box plants, including using natural predators, applying insecticides, and using physical barriers. It’s important to understand that it’s not only the caterpillars but also the moths or butterflies that lay eggs on the leaves that need to be considered. It’s best to adopt a multi-pronged approach to effectively control caterpillars on box plants.

Which Comes First, the Caterpillar or the Moth?

The caterpillar comes first, followed by the moth or butterfly. The life cycle of a moth or butterfly typically begins with an egg, which is laid by an adult female on a suitable host plant. The egg hatches into a larva, which is the caterpillar stage. The caterpillar then feeds and grows, shedding its skin multiple times as it does so. Eventually, the caterpillar will enter the pupal stage, during which it will undergo metamorphosis into an adult moth or butterfly. The adult will then emerge from the pupa and begin reproducing, laying eggs to start the cycle anew.

During the adult stage, moths and butterflies will typically feed on nectar from flowers and other sources of sugar, while the caterpillars eat the leaves and foliage of host plants. Different species of moths and butterflies will have specific host plants that their caterpillars will consume. For example, box plant caterpillars will only feed on box plants, while adult moths and butterflies might feed on different plants. It is important to identify which species of caterpillars are eating your box plants so you can target the control methods specifically.

How to Control the box eating caterpillar

There are several methods that can be used to control box-eating caterpillars, including:

  1. Natural predators: Encouraging natural predators such as ladybugs, lacewings, and parasitic wasps can be an effective way to control caterpillars. These predators feed on both eggs and caterpillars, helping to keep populations in check.
  2. Handpicking: This method involves physically removing the caterpillars from the plants. This can be done by hand or with the use of gloves, and the caterpillars can be disposed of or placed in soapy water.
  3. Insecticides: There are a variety of insecticides that can be used to control caterpillars. These include Bacillus thuringiensis (Bt), neem oil, and insecticidal soap. It is important to follow the instructions on the label when using insecticides and to be aware of the potential effects on non-target organisms.
  4. Physical barriers: Applying a physical barrier such as horticultural fleece can prevent adult moths and butterflies from laying eggs on your box plants.
  5. Cultural control: You can also try to change the environment of your plants to make them less hospitable to the caterpillars. For instance, maintaining a clean and healthy garden free of debris, creating a habitat for beneficial insects and birds, or cleaning up fallen leaves and twigs can be a good way to keep the caterpillar population low.

It’s worth noting that different species of caterpillars may have different behaviour and feeding habits and will require specific methods to control them effectively. It is also recommended to consult with a local expert or professional for best practices for your specific case.

How to use Xentari Caterpillar Killer

Xentari is a brand of biological insecticide that contains the active ingredient Bacillus thuringiensis (Bt), a naturally-occurring soil-dwelling bacteria that is toxic to certain insects, including caterpillars.

When using Xentari, it is important to follow the instructions on the label carefully. Here are some general steps to consider:

  1. Mix the Xentari product with water according to the label’s instructions.
  2. Spray the solution directly on the foliage of your box plants, making sure to thoroughly cover the leaves and the stem.
  3. Spray the solution in the evening or early morning when the temperature is cool, and the plants are less likely to be damaged by the spray.
  4. Repeat the application after 7-10 days, or as directed on the label, to ensure that newly hatched caterpillars are also controlled.
  5. Avoid spraying when the weather is too hot or sunny, as it can cause damage to the plant.
  6. Keep in mind that BT products work by being ingested by the caterpillars. It can take some time before seeing the results.
  7. Also, using other methods like handpicking, using physical barriers, and promoting natural predators to achieve better control.

It’s always important to read the label for specific usage instructions and precautions before applying any pesticides. Additionally, make sure to always wear protective gear, such as gloves and a mask, when handling any pesticides to protect yourself from any potential harm.

Do the Boxwood Moth Pheromone Traps work?

Boxwood Moth Pheromone traps can be an effective tool in controlling boxwood moth populations, but it’s important to note that it should not be considered the sole solution.

Pheromone traps work by mimicking the pheromones (sexually attractant chemicals) emitted by adult female moths, which can attract adult males to the trap. Once the males are trapped, they are unable to mate with the females and thus unable to reproduce, which can help to reduce the overall population.

It’s important to use these traps in the appropriate time frame and place, as the pheromones used in the trap will only attract adult boxwood moths of the specific species. Generally, traps should be installed before the adult boxwood moths begin flying, usually in the late spring or early summer. These traps should be placed in the area where the boxwood plants are located. This way, the pheromones will attract the male moths to the trap.

It’s also worth noting that these traps should be monitored and replaced frequently, as the pheromones will lose their effectiveness over time.

While pheromone traps can be a helpful tool, they should be used in conjunction with other control methods, such as the use of natural predators, cultural control, or insecticides. It’s also important to keep monitoring your plants for caterpillars or eggs and pick them by hand or use other methods of control.

Consult with a local expert for best practices for your specific case.

It’s also important to consult with a local expert or professional for best practices for your specific case and for identifying the species of caterpillar that is affecting your box plant.

Can Box Plants Recover from Caterpillar?

Box plants can recover from caterpillar damage, but the extent of the recovery will depend on the severity of the damage and the timing of the infestation.

If the infestation is caught early and the caterpillars are removed before they cause significant damage, the box plants will likely recover with minimal impact. However, if the infestation is allowed to persist and the caterpillars are able to consume large amounts of foliage, the box plants may suffer significant damage and require time to recover. In this case, the growth may be stunted, and the overall appearance of the plant may be affected.

It’s important to note that during the recovery process, the box plant may be more susceptible to further damage from pests and diseases, so it’s important to continue monitoring the plants and taking appropriate measures to protect them.

In some cases, it may be necessary to prune heavily damaged branches or even remove and replace badly affected plants if the damage is severe and the plants can’t recover by themselves.

To ensure box plants recover as quickly as possible, it IS recommended to use a combination of approaches like handpicking the caterpillars, using physical barriers, promoting natural predators, and using insecticides when appropriate. Also, providing the plant with optimal growing conditions and proper care can support the plant’s recovery process.


In conclusion, caterpillars can be a significant problem for gardeners when they start eating box plants in the UK. However, there are a variety of methods that can be used to control caterpillar populations and protect your box plants. 

These include using natural predators, applying insecticides, handpicking, and using physical barriers. It’s important to consult with a local expert or professional for best practices for your specific case and for identifying the species of caterpillar that is affecting your box plant. 

It’s also important to keep monitoring your plants for caterpillars or eggs, maintain a clean and healthy garden, and use a multi-pronged approach to ensure that the caterpillars are effectively controlled. With proper management, box plants can recover from caterpillar damage, but it may take some time. Taking the appropriate measures and providing proper care to the plant can support the recovery process.