The Horse-Chestnut Leaf-Miner (Camararia ohridella

The Horse-Chestnut Leaf-Miner (Camararia ohridella) hunt.
A student was asking people to take part in a survey checking Horse Chestnut trees for leaf miners on trees.. The 'mines', look like little brown circles or lines. When held up to the light they are easier to see.

Horse chestnut leaf miner was first found established in the UK in the London Borough of Wimbledon in July 2002 and it is now present across most of south-central England, East Anglia and the Midlands.