Box Tree Caterpillar UK: Which Areas Are Worst Affected?
Box tree caterpillar has been in the UK since 2008 and in private gardens since 2011. It started in south-east England and has spread relentlessly. As of 2026 it is found across virtually every region. But severity varies enormously by location. This guide maps the current situation region by region.
The Spread — A Brief Timeline
2007 - First intercepted at UK ports
2011 - First in private gardens (London/south-east)
2014-2016 - Rapid expansion across southern England
2018 - First recorded Scotland (Fife) and Cornwall
2019-2021 - Reached Wales, Midlands, East Anglia
2022-2024 - Effectively UK-wide
2024 - RHS reported 5x increase in sightings vs 2023
Regional Breakdown
| Region | Severity | First Recorded | Key Details |
|---|---|---|---|
| London & Greater London | Very High | 2011 | Epicentre. Year-round activity. Multiple generations. All boroughs affected. |
| Surrey/Kent/Sussex | Very High | 2012 | Among first areas after London. Heavy infestations in residential and public gardens. |
| Essex/Hertfordshire/Berkshire | High | 2013-2014 | Strong established populations. Garden centres a vector. |
| Hampshire & South Coast | High | 2014-2015 | Warm coastal climate favours multiple generations. |
| West Midlands | Medium-High | 2016-2017 | Growing rapidly. Urban areas particularly affected. |
| East Anglia (Norfolk/Suffolk/Cambs) | Medium | 2017-2018 | Established but less dense than south-east. |
| South West (Somerset/Devon/Cornwall) | Medium | 2018 | Cornwall first recorded 2018. Spreading inland. |
| Wales | Medium | 2018-2019 | South Wales worst affected. Spreading north. |
| East Midlands/Yorkshire | Medium-Low | 2019-2020 | Emerging. Urban centres first. |
| North West (Manchester/Liverpool) | Low-Medium | 2020-2021 | Patchy but increasing. |
| North East/Cumbria | Low | 2021-2022 | Isolated sightings. Expected to increase. |
| Scotland | Low | 2018 (Fife) | Isolated sightings in south. Not yet widespread. |
| Northern Ireland/Ireland | Low | 2020+ | Early stage. Monitoring recommended. |
Recommended
TOPBUXUS ABC — Anti Box Tree Caterpillar — 15 g treats 150 m² · 5 × 3 g sachets
Why the South-East Is Worst Hit
The south-east remains the epicentre of box tree caterpillar infestation in the UK due to a combination of factors. First, it was the point of original establishment, meaning the pest has had the longest time to build up populations. Second, higher temperatures in the region favour multiple generations per year, allowing rapid population growth. Third, the south-east contains high concentrations of box gardens in close proximity, particularly in residential areas and public gardens, providing abundant food resources. Fourth, the horticultural trade—with many nurseries and garden centres in the south-east—has been a significant vector for spread, both locally and to other regions.
How Box Tree Caterpillar Spreads to New Areas
Box tree caterpillar spreads to new areas through two main mechanisms. Natural moth flight is one: the adult moths are strong fliers capable of travelling several kilometres in search of mates and fresh box plants. However, natural flight alone is relatively slow and localised. The second and far more significant vector is human-assisted transport via infested plants through the nursery trade. A single infested box plant sold from a nursery can establish a new population hundreds of kilometres away. This is the primary mechanism responsible for the rapid, long-distance spread of box tree caterpillar across the UK.
What Should You Do In Your Region?
High severity areas (London, south-east): Treatment is essential every year. Deploy traps, treat with XenTari minimum twice per generation, consider alternatives for less important hedging.
Medium severity: Monitor actively from March. Treat at first sign. Deploy pheromone traps.
Low/emerging: Deploy pheromone traps for early detection. Inspect new box purchases. Be prepared to treat.
All regions: The caterpillar IS coming if it hasn't arrived yet. Preparation beats reaction.
TOPBUXUS ABC — Anti Box Tree Caterpillar
15 g treats 150 m² · 5 × 3 g sachets
The current TOPBUXUS Bacillus thuringiensis product and the direct replacement for the XenTari sachets UK gardeners have used for years. Caterpillars stop feeding within about an hour and die within a few days.
What works
- Stops feeding within about an hour
- Completely safe for bees, birds, pets and children
- Five separate 3 g sachets — no waste, no scales needed
- Three-year shelf life, so a box lasts several seasons
What to watch
- Only works if the spray reaches inside the plant
- Needs re-applying every 7–10 days during an active generation
- Degrades in UV — has to go on in the evening
TOPBUXUS Box Tree Moth Trap
Delta trap + 2 pheromone lures — a full season
A pheromone trap will not clear an infestation, but it tells you exactly when the moths are flying. Covers up to 200 m². Two lures included: one in mid-April, the second in mid-July.
What works
- Removes the guesswork from spray timing
- Two lures cover a whole season
- Covers up to 200 m² — enough for most gardens
- Reusable body; only the lures need replacing
What to watch
- Will not control an infestation on its own
- Catches males only
- Needs hanging by mid-April to be useful
Frequently asked questions
Is box tree caterpillar in my area?
As of 2026, box tree caterpillar is found across virtually all of England and Wales, with established populations in most of Scotland. Even if it has not been formally recorded in your specific locality, it is highly likely to arrive within the next year or two. The best approach is to assume it is in your region and take preventive measures.
Will box tree caterpillar reach Scotland?
Box tree caterpillar has already been recorded in southern Scotland (Fife) since 2018. Spread to other parts of Scotland is expected and will likely accelerate, especially if transported via infested plants. The cooler climate of northern Scotland may slow reproduction, but complete evasion is unlikely.
Is box tree caterpillar worse in cities?
Yes. Urban heat island effects in cities and large towns create warmer microclimates that favour multiple generations of box tree caterpillar per year. Additionally, cities often contain high densities of box hedging and topiary in close proximity, facilitating rapid spread. Rural areas with scattered box plants typically experience lower infestation pressure.
Can I report box tree caterpillar sightings?
Yes. Sightings can be reported to the RHS (Royal Horticultural Society), Butterfly Conservation, or your local plant health authority. Photographs are helpful. Reporting contributes to national monitoring and helps inform pest management strategies.
Will box tree caterpillar ever be eradicated from the UK?
No. There is no realistic prospect of eradication. Box tree caterpillar is now established across the UK and has access to a year-round food source (box plants). The focus has shifted from eradication to management and containment at the regional and garden level.
Read next
Box Tree Caterpillar 2026: What UK Gardeners Need to Know
What to expect from the 2026 box tree caterpillar season, a month-by-month spray calendar, and the five things to do right now.…
ReadWhen to Spray for Box Tree Caterpillar (UK Timing Guide)
Timing decides whether Bt works. Here is exactly when to spray in the UK, how to know a generation has started, and why April ma…
ReadHow to Identify Box Tree Caterpillar: 7 Signs to Look For
Frass, webbing, skeletonised leaves and bark stripping — the seven signs of box tree caterpillar, with photographs of each one.…
Read