Article: When Do Box Moths Appear in the UK? (2026 Guide)
When Do Box Moths Appear in the UK? (2026 Guide)
Box moth activity in the UK follows a fairly predictable seasonal pattern. Understanding when box moths appear in the UK is one of the best ways to prevent serious box hedge damage, because it helps you time monitoring and treatment before caterpillar populations explode.
If you’re looking for the most effective approach, start with our complete guide to treatment: Box Tree Caterpillar Treatment UK – Complete Guide.
UK Box Moth Season: When to Watch
In most parts of the UK, adult moths begin to appear from late spring, with peak activity typically between May and August. In warmer years, you may see extended activity and an increased risk of a second generation later in the season.
March–April
Overwintered caterpillars can become active as temperatures rise. This is the time to inspect hedges closely for early signs such as webbing, droppings, or leaf damage.
May–June
Adult moths emerge and lay eggs on the underside of box leaves. If you’re using traps, this is when you’ll often start seeing activity.
July–August
This is commonly the period of peak feeding damage. Many UK homeowners only notice the problem once browning patches appear — but by then, a hedge may already be under heavy pressure.
September–October
A second generation of caterpillars may develop before winter. Continued monitoring is key, especially in mild years.
Why Timing Matters for Treatment
The most effective box tree caterpillar treatment is applied when larvae are actively feeding. Treating too early or too late reduces effectiveness. Understanding the box tree caterpillar life cycle will help you predict when eggs hatch and caterpillars begin feeding.
Signs Box Moths Have Arrived
- White moths with brown-edged wings flying near box hedges (often at dusk)
- Eggs on leaf undersides
- Fine webbing inside the hedge
- Small green caterpillars and droppings
What to Do When Box Moths Appear
- Inspect the entire hedge (including inner growth).
- Remove visible caterpillars where possible.
- Apply treatment during dry conditions at the right time.
- Monitor weekly for further signs of activity.
- Repeat treatment if a second generation appears.
For products and solutions, explore our box tree care range here: Box Tree Care & Treatments.
If you’re deciding on an approach, you may also find this useful: Best Treatment for Box Hedge Caterpillars (UK Guide).
Next step: For a complete step-by-step plan, see our Box Tree Caterpillar Treatment UK pillar guide.
