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Horse Chestnut Leaf Miner

Pest

The horse chestnut leaf miner is a tiny moth whose larvae tunnel inside the leaves of horse chestnut trees. While it rarely kills a healthy tree, it causes significant browning and premature leaf drop that can make the tree look quite sickly by late summer.

Symptoms by part

Leaves

Small, white, winding mines or blotches appear on the leaf surface, which eventually turn brown and cause the leaf to curl or wither.

Causes

  • The presence of adult moths in the area during the growing season.
  • Mild winters that allow more larvae to survive in fallen leaf litter.

Could be confused with

  • Guignardia leaf blotch · This is a fungal disease that creates large, irregular reddish brown spots with a yellow halo, rather than the distinct winding tunnels of the leaf miner.

Treatment

  1. Rake up and destroy all fallen leaves beneath the tree in autumn to remove overwintering pupae.
  2. Compost fallen leaves at a high temperature or bury them deeply to prevent moths from emerging in spring.
  3. Install pheromone traps in the canopy during the warm growing season to disrupt the mating cycle of adult moths.

Without chemicals

  • Thoroughly clear and dispose of all leaf litter from under the tree canopy every autumn.
  • Encourage natural predators like birds and parasitic wasps in the garden to help manage moth populations.

Preventing it

  • Maintain high garden hygiene by removing leaf debris every year.
  • Encourage biodiversity in the garden to support natural enemies of the moth.

Season

The warm growing season.

Spread risk

High

Severity

Low

When to act

Act in autumn by clearing leaves to reduce the population for the following year. There is no need to remove the tree as it will typically recover its health in the next growing season.

Think it's Horse Chestnut Leaf Miner?

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Questions people ask

Will this pest kill my horse chestnut tree?
No, it is primarily a cosmetic issue. The tree may look unsightly, but it usually survives and leafs out normally the following year.
Why do the leaves turn brown so early?
The larvae feed on the tissue inside the leaf, which destroys the chlorophyll and causes the leaf to dry out and brown prematurely.

Plants it affects

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This guide was generated with AI and is general information, not horticultural advice. Read about how we build these guides.