As often happens, I was alerted to the existence of this leafminer by a post on Twitter of someone else finding one. So, in the following days, I pointed my walking shoes in the direction I knew I would find their host plant for a little leaf staring, and Bob’s your uncle (such a strange expression, don’t you think?)! After checking two or three clumps of Hemp-agrimony (Eupatorium cannabinum), I spotted the tell-tale feeding signs (see photos below) and, lurking beneath a leaf, my first Coleophora follicularis (Agrimony case-bearer).

According to the British Leafminers website, as well as feeding on Hemp-agrimony, these larvae also feed on Common fleabane (Pulicaria dysenterica) and Ploughman’s-spikenard (Inula conyzae), and the times of year of the appearance of the larvae and adults vary depending on the larval food plant. When Hemp-agrimony is used, the mines can be found in April-May and then again in July-August. The UK Moths website shows an adult moth that has a subtle pattern of beige and cream stripes, a smart-looking little flier.