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We need your help. Across the country that symbol of autumn, the horse chestnut tree is under attack from an invading moth. The horse chestnut leaf-miner moth or was only discovered in 1985. But since then it has spread from near Macedonia to much of Europe including the UK. It was first noticed in this country in Wimbledon. Since it's known to travel on the clothes of people it is possible it was brought here by a visitor to the famous tennis tournament. But that's just a theory. You can see how quickly the moth has spread .

It's the caterpillars that cause the damage. As you might expect from the name they live inside the leaf and mine their way through it. Leaving small, brown, dead-spots behind them. But with thirty caterpillars to a leaf you can easily have a hundred thousand of them in just one tree.

Horse chestnut leaf-miners are lucky. They've hit a sweet spot in nature's calendar where there are few potential predators about.

This means they can get through seven or more breeding cycles. Devastating and eventually killing off the leaves of the infected tree.

And many of the brown leaves laying on the ground through the winter contain dormant moth pupae ready to start the cycle all over again when the weather warms up.

We'll be returning to this story in the Spring with details of an experiment we can all do to understand more about this moth. But in the meantime take a closer look at your conker trees. Using you can learn what the damage looks like and report any outbreaks near you.

And on top of that do leave your thoughts and sightings in the comments below.

UPDATE

In the comments EnglishFolkFan asks about the best ways to deal with infected leaves. Bury or burn them is the short answer. In Cheltenham the conker trees in the centre of town are noticeably healthier than those in the parks. That's because in the town centre the council sweeps up and disposes of the fallen leaves. Obviously they're doing this to keep the town tidy but it also gets rid of infected leaves containing the moth pupa. This is how the moth survives the winter before reappearing when the weather warms up. So you can try and control things by burying the leaves in your garden or putting them all on a bonfire. Composting appears to be less effective. You can read more about control of this problem .

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