One of the most successful invasive moths of recent years, the damage it causes to the leaves of Horse Chestnut can now be seen almost everywhere in the county. It was first described from near Lake Ohrid in what is now North Macedonia as recently as 1985 but it appeared to be already well established in the area. From there it spread dramatically across Europe possibly aided by the road and rail network and was first recorded in Britain from Wimbledon in 2002 but again it was already well established and may well have arrived at least a year earlier. The first county record was of 3 leaf mines in Hollinside Wood just south of Durham city on 25th October 2010 and the first adult was taken at light just 2 years later at Chester-le-Street on 13th August 2012. The distinctive leaf mines can be found all year round and the almost equally distinctive adults have been found from late April through to early October.