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First of all, it’s worth noting that both box blight and box caterpillar can occur simultaneously on the same box hedge, further complicating the situation.

With that said, they are both two distinct challenges that affect boxwood and in this short article we are going teach you how to spot the difference between Box Blight vs Box Caterpillar.

While they can cause similar symptoms like leaf damage and defoliation, there are key differences that can help you identify the problem that you’re having.

Let’s explore how to tell the difference between box blight and box caterpillar.

Box Blight:

If you are a gardening enthusiast or love beautiful Buxus balls, hedges, pyramids or any other shapes you like to create –  you may have come across the term “box blight“.

box blight vs box caterpillar

Box Blight



Box blight mainly manifests as dark brown or black round spots on leaves.

These spots may be surrounded by a yellow halo.

The disease can progress rapidly, causing severe foliar damage and defoliation.

Dead branches:

In addition to leaf spots, box blight can cause young shoots and shoots to go brown and die, resulting in twig dieback.

This can lead to an overall decline in the health of the hedge.



In wet conditions, you may notice the presence of white cotton-like masses on the affected leaves or stems.

These structures are the spore-producing organs of the fungus responsible for box blight.

Environmental conditions:

Box blight thrives in cool, humid environments with poor air circulation.

It is most common in areas with high humidity, frequent rainfall, or excessive watering.


Box Caterpillar:

Caterpillar Appearance:

If you look carefully, you can occasionally see the caterpillars feasting on your hedge.

The original box caterpillars are pale yellow larvae with black stripes along the body. When mature, they are brilliant green with pronounced black stripes. They have visible legs and heads.

box caterpillar vs box blight

A selective focus shot of box caterpillar on box hedge

Defoliation and webbing:

Box caterpillar are known for their feeding habits. They gobble up box hedges, often resulting in severely damaged leaves and exposed skeletal like outer leaf.

They create silk webs in the foliage, providing shelter for themselves.

box caterpillar webbing and skeletal leaves

The presence of butterflies:

Box caterpillars turn into adult butterflies known as box moths.

These butterflies have distinctive white wings with brown edging.

You may see them flying around infested box hedging, especially at night.

Seasonal Activities:

Box caterpillar are most active from April to October, with their feeding and infestation peaking during this time.

They can go through several generations in a single growing season.


So as you can see above, those are the main differences between box blight and box caterpillar.

You can also use washing up liquid to help kill off box caterpillar. There are certain box caterpillar treatments that target these pesky bugs too.

However, if you wish to understand more about box blight and the box caterpillar please read on.

Understanding Box Blight

box blight vs box caterpillar

Box blight, scientifically known as Cylindrocladium buxicola and Volutella buxi, is a fungal disease that specifically affects boxwood shrubs (Buxus).

It can be quite frustrating to witness an outbreak of box blight, as it can cause significant damage and even lead to the decline of your beloved boxwood and knot gardens.

This is a real pain especially with the amount of time it takes to create a knot garden or any other Box shapes.

Box blight thrives under specific environmental conditions.

It is more common in areas with high humidity, inadequate air circulation, and frequent rainfall or irrigation.

These conditions create an ideal breeding ground for fungal spores to spread and infect boxwood trees.

Additionally, the disease can be spread through contaminated soil, splashed water, or infected garden tools.

If you’ve cut some hedging and you suspect there may be box blight, I recommend cleaning the tools used before cutting the next box hedge to avoid passing it on.

Manage box blight:

While box blight can be difficult to completely eliminate, there are management strategies that can help minimize its impact and prevent its spread:

More Box Blight

Pruning and cleaning:
Promptly remove and dispose of any infected plant material, including dead leaves and pruned branches.

This reduces the chance of spores spreading to healthy plants.

Improved airflow:
Space your box tree properly to allow for better air circulation.

This helps reduce moisture around the foliage, creating a less favorable environment for boxwood blight to develop.

Avoid overhead watering:
Water the boxwood tree at the base instead of using overhead watering methods.

Wet leaves can promote the growth and spread of fungal spores.

In severe cases, a special fungicide to control boxwood blight may be considered.

Consult a horticulturalist or local gardening center for suitable products and follow the instructions carefully.

Box blight can be a challenge for boxwood enthusiasts, but with the right identification, timely prevention and management measures, its impact can be limited; By being vigilant, maintaining good garden hygiene, and providing optimal growing conditions, you can help protect your beloved boxwoods from the grip of this fungal disease.


Understanding Box Caterpillar

In the blissful world of gardening, sometimes unexpected guests can appear, posing challenges to the health and beauty of our beloved plants.

One of the guests that has caught the eye in recent years is the ‘Box Caterpillar’.

This tiny creature, with a voracious appetite for boxwood foliage, has gardeners worried.

Here, we’ll explore the fascinating world of the box caterpillars, unravel its mysteries, and provide insights into its identity, behavior, and ways of life.

Close-up of a box tree moth (Cydalima perspectalis) climbing down the leaves of a box tree.

Curious Box Caterpillar:

The box caterpillar, scientifically known as Cydalima perspectalis, is the larval stage of a butterfly native to Asia.

This invader has infiltrated various parts of Europe and North America, causing alarm among gardeners and enthusiasts who love their box hedges.

While the presence of the caterpillars and moths may seem intimidating, understanding their characteristics is the first step to effective management.

Managing infestations:

While controlling box caterpillar may seem daunting, there are effective strategies to manage their presence and minimize the damage they cause:

Manual removal:
Regularly inspect your box hedge and remove the caterpillars and their webs manually.

Wear gloves to protect your hands and dispose of them appropriately (like standing on them.. half kidding)

Biological control:
Encourage natural predators, such as birds and beneficial insects such as parasitic wasps and beetles, into your garden.

These predators feed on box caterpillars, which help to reduce their populations.

Pheromone traps:
Pheromone traps are available to monitor and trap adult caterpillar, which can help reduce mating and subsequent caterpillar infestation.

However, these traps are most effective when used in combination with other control methods.

In the event of a severe infestation, a specially formulated insecticide for caterpillar control may be considered. It’s essential to choose products that are safe for other insects such as bees for example – always follow the instructions provided.

While the box caterpillar may seem like a formidable challenge, understanding its life cycle, appearance and behavior will give you the tools to effectively manage its impact.

By being vigilant, taking precautions, and using proper control methods, you can protect your beloved knot gardens from the voracious appetites of these little guests.

So hopefully this article has helped you out when it comes to understanding box blight vs box caterpillar, if you have any questions you would like answered please feel free to keep in touch.

If you found this article useful, why not check out some of our other shrub guides here.

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