What's happening to our conker trees?

New (23rd Jan 2014): The frst scientific results of the Conker Tree Science project are published in the scientific journal PLOS ONE. Download and read the article here.


Mission: bird attacks | See results | Mission: alien moth survey | Blog

Our conker trees are under attack by 'alien' invaders! Take part in real science to discover more about conker tree health by taking part in our missions.

Have you noticed whitish patches on the leaves of horse chestnut trees?  By the middle of summer, the whitish patches die and turn brown.  Sometimes whole trees turn brown, and it looks like autumn has come early.

The damage is caused by a tiny 'alien' species of leaf-mining moth, which is invading the UK.  For biologists, an 'alien' is a species not naturally found in an area or habitat.  The moth’s caterpillars eat the leaves from the inside.  Infected trees are weakened, and produce smaller conkers.

Luckily, there is help at hand. Some of the leaf-mining moths are killed by birds that prey upon the caterpillars. Others are killed by natural pest controllers, in the form of tiny insects.  These insects lay their eggs inside the caterpillars of the leaf-mining moths, and when the eggs hatch, the larvae slowly eat the caterpillars, eventually killing them.

Joining in today. Register today to receive news about the research and reminders when to take part and then,

Take part in the missions:

Mission: bird attack - from 28 August 2013

  • Help to discover how birds are responding to the alien moths. Are they attacking the caterpillars?
  • This mission is for everyone who can find an affected horse chestnut tree.

Mission: alien moth survey - from 15 June 2013

  • Help to find out how far the invading moth has spread and the damage it is causing, by submitting records from your area.
  • Find out what to look for.
  • Take part in the Mission: alien moth survey with our Leaf Watch app for iPhones and Android smartphones.

Conker Tree Science Leaf Watch logo

Mission: pest controllers 

(Now finished for this year - see results)

  • Help to discover how many alien moths are being killed by pest controllers, by collecting leaves and recording which insects hatch out from them.


  • To receive the results of the research and to take part in the missions.


Damaged leaf, showing whitish leaf mines 
(photo: Michael Pocock)

Michael Pocock, one of the scientists studying the moths, explains his research

Adult invasive moth (photo: Rich Andrews)
A tiny alien moth that got away from the pest controllers
(photo: Rich Andrews)

Collect leaves like these to find out more about the alien moth and the pest controllers
(photo: Rich Andrews)