Cosmopterix pulchrimella was first recorded in Britain in 2001 at Walditch in west Dorset. Since then it has been spreading along the coast and it has been common at Portchester in east Hampshire for several years. There are no records in West Sussex so for the last couple of years I've paid a visit to Bosham around this time of year, to look for the larval mines in Pellitory-of-the-wall. Each visit has been unsuccessful until a couple of days ago when I found half a dozen occupied mines.
The larvae will turn into a rather stunning little moth.