About the moth 1

The horse-chestnut leaf-mining moth

The moth whose caterpillars are causing the damage to horse-chestnut trees is the horse-chestnut leaf-mining moth, which has the scientific name Cameraria ohridella.

It is known as one of the 'micro moths', to distinguish it from the typical 'macro moths', which are the larger moths often attracted to light.

A mating pair of horse-chestnut leaf-mining moths. © Dave Kilbey

The adult moth

The adult moth is tiny - just a few millimetres long - and very attractive, with white stripes on glossy bronze wings. Many people we have spoken to are surprised that the moth is so small. When the adults emerge, there can be so many flying close to a horse-chestnut tree that the tree appears to shimmer.

Its leaf-mining larvae

It is the larvae (or caterpillars) of the horse-chestnut leaf-miner that do the damage and feed on the leaves of the horse-chestnut. Many caterpillars are external feeders, but the horse-chestnut leaf-miner is different. Its larvae actually live inside the leaf and they 'mine' the leaf forming what are called, unsurprisingly, leaf mines. As they feed on the green tissue on the inside of the leaf, they leave the upper and lower layers of the leaf (the 'epidermis) intact, so the larvae remain protected.

The remaining epidermis of the leaf is translucent, which is why the leaf mines look whitish when they are fresh. After a few weeks the epidermis of the leaf mine dies and turns brown.

Each larvae produces a singe leaf mine, which eventually ends up about the size of half a person's finger. When infestations are large, the mines coallese and the larvae form groups searching for the remaining green tissue.

The larvae have incredible adaptations for living inside a leaf. They are have flattened so they can easily move about in the leaf mine and they have chisel-shaped heads with pointed moutparts so they can easily eat the fresh green tissue at the edge of the leaf mine.

Mission: pest controllers

Conker Tree Science

Can tiny parasitic wasps help to save our conker trees?

Believe it or not there are dozens of different kinds of tiny wasps (only distantly related to the stinging wasps that we are so familiar with) that attack the horse-chestnut leaf-miner. These wasps are so small that they lay their eggs inside the leaf-miner as it is eating the horse-chestnut leaf from the inside out! The developing wasp larvae eat the leaf-miner from the inside out and then burst out of the caterpillar, in the process killing it and so acting as a natural pest controller.

Can these potential pest controllers actually help by parasitising enough of the leaf-miners to control it's numbers? Given that we have so many of the leaf-miners in this country it would seem that they cannot, but we are interested in finding out more about them.

Stephen Turner - The art of the horse-chestnut

Stephen Turner has produced a fascinating blog about his experience as artist in residence at Sturovo in Slovakia (Hungarian / Slovakian border) over the past 6 months.

Conkers painted in watercolour made from the tree itself, from Stephen Turner's blog of his artistic residency in Slovakia.

He has been creating a visual art project about the leaf mining moth and the horse-chestnut in these locations which has involved mapping the location and spread of the disease amongst this species of tree in Sturovo and Esztergom (i.e. both sides of the river Danube) and he has produced a lovely narrative of his discoveries and creations.

Featuring in the Observer Ethical Awards

As part of the Observer Ethical Awards, Lucy Siegle, who runs the awards, wanted something for voters to do once they had voted. She invited me (Michael Pocock) and Darren Evans to create an invasive species citizen science project. Of course, being so involved in Conker Tree Science, we had to include the horse-chestnut leaf-miner as one of the featured species!

We chose to make sure that people were invited to submit records for all the 10 species to recording schemes that were already running, so that the data really would be useful and that the excellent work so many organisations are doing will get promoted. It was just a shame that the Observer project was promoted during the winter when many of the species were dormant. We hope that people will continue to report these species during this summer and that it will raise awareness of the potential problems of invasive species.

News that was on the website

Here we've put the old news that is archived from the website. We'll put it in blog posts in due course.

News Archive (2010-11) 

• 15 Jan 2012. Conker Tree Science is one of the projects featured in our invasive species recording project with the Observer.
• 16 Sep 2011. Darren and Michael are on The One Show (BBC1 TV) talking about the project. This follows recent press coverage in the Daily Mail, The Telegraph, The Sunday Times and BBC Radio 4's Farming Today.
• 28 July 2011. Stephen Fry likes our app! Join with the thousands of others and take part in the Mission: alien moth survey with the app or via this website.
• 19 July 2011. Our app is featured on BBC Midlands Today television program.
• 18 July 2011. Our iPhone app is in the top ten 'new and newsworthy' apps on the App Store.
• 14 July 2011. Conker Tree Science is featured on BBC Radio Leeds and ITV Yorkshire's Calerdar program.
• 8 July 2011. The Conker Tree Science: Leaf Watch app honoured as a 'New & Noteworthy' iPhone Education app and the Android version is described as 'rather excellent'. Excellent critical acclaim for the team that developed it.
• 7 July 2011. Conker Tree Science is featured in the Guardian, BBC Radio Bristol and BBC Radio Nottingham.
• 6 July 2011. Read our press release.
• Results from both missions in 2010.
• Take part in Mission: alien moth survey with our new Leaf Watch app for iPhones and Android smartphones.
• Article on the identification of the species of pest controllers published in British Wildlife.
• Conker Tree Science features on Autumnwatch Unsprung (14 October 2010) and BBC Radio Humberside (15 October 2010).
• Now that conkers are out, the results of Conker Tree Science are again in the news: BBC Midlands Today (7 October 2010) and The Independent (3 October 2010).
• Listen again to Dr Michael Pocock on BBC Radio 4's Material World (26 August 2010).
• See our blog on NERC's Planet Earth Online (12 July 2010).
• Conker Tree Science is featured in Times Higher Education (24 June 2010).
• Listen again to Dr Darren Evans on BBC Radio 4's Material World (10 June 2010).
• 6 June 2010 - the first leaf mines are spotted in Bristol!  They are only a couple of millimeters in diameter.
• Our missions in a nutshell - download the Conker Tree Science flyer, as featured at Cheltenham Science Festival and Bristol Festival of Nature.
• Conker Tree Science is featured on BBC Breathing Places and on SchoolScience.
• We had a fantastic response from Bristol school children who helped with a similar project in 2009. See the BBC video clip about it.

The One Show

Conker Tree Science went national on the telly today! Darren and Michael were inviewed for a piece for The One Show (BBC1 TV) talking about the project, especially about the Leaf Watch smartphone app. 

This follows recent press coverage in the Daily Mail, The Telegraph, The Sunday Times and BBC Radio 4's Farming Today.

When will the moth get to Ireland?

Across the Irish Sea they are aware of the risks posed to their horse-chestnut trees, according to an article in the Irish Times by the naturalist Michael Viney.

Whenever it arrives, it will almost certainly come across in someone's car, crossing on the ferry. My guess would be that it will be first found in a town near a port in south of the island (maybe Cork or Dublin) in about 5 years' time. It could easily come from someone in a town in England or Wales who was packing their car boot under a horse-chestnut tree and some of the moths got in the boot but by mistake, survived the journey and they escaped when the car was unloaded.