Last Wednesday, a small number of us that are interested in observing and recording the larvae and feeding signs of leaf mining moths – moth larvae that feed within a leaf - met with aim of recording as many of these moth species as we could in a single day. I was very much the novice of the group. Our venue was the Forest of Flowers project, located to the north of York, that has 74 acres of newly created woodland and wildflower meadow; a majestic location despite dull conditions.

Our first task was to help identify the contents of three moth traps set over night. While there are never going to be many moth species in a trap mid-October, one came as a bit of a surprise. Musotima nitidlais, the Marbled Fern, had been recorded for the first time in Yorkshire, on the coast at Easington, only nine days earlier. With three other coastal records that week, people had speculated as to how long it would take the moth species to be recorded in land. Here was the answer. The moth, native to Australia and New Zealand, was accidentally introduced to the UK and first recorded in Dorset in 2009. The species has been spreading north since. With its food plant being ferns, including bracken, the moth has the potential to become a regular sighting here in Wharfedale.

There is much to consider when identifying leaf mines. Firstly, what plant species is the larva feeding on as many, but not all, leaf mining moths are plant specific. What type of mine is it? Perhaps a blister like those of phyllonorycter species (Phyllonorycter cerasicolella, the cherry leaf-miner, on wild cherry being the example pictured) or a gallery mine as for stigmella species. Where was the egg laid on the leaf? Where is the frass (poo) and what colour and pattern does it have? If the mine is tenanted, there are clues there too.

Our progress is akin to a botany walk. We often joke about such excursions not making it beyond the car park, owing to the diversity of plant life that can be recorded there. Over a 6-hour period a mere two kilometres was covered. While slow, we did find 72 leaf mining moth species, many of which would never be caught in a moth light trap.

It will be intriguing to return to Forest of Flowers in early summer when the meadows are in flower. By then, many of the moth larvae we recorded should be on the wing laying the eggs of the next generation. It has been fascinating to observe how many insects have made this place their home in just a few years since the project began.

wharfedale-nats.org.uk