Five species of Lepidoptera larvae can be found in the leaves of Beech (Fagus species) and, with a lot of searching, much head-scratching, some rejections, and the much appreciated assistance of our county moth recorder Dave, I’ve now found and positively identified all five in my local area.
Stigmella tityrella: This moth’s larval leaf mines featured in last week’s post about green islands. The gallery (like a corridor) mine is usually compact and angular and, in particular, the larva stays between the veins when creating its mine – that is the feature I find helps most with its identification. As you can see from the two mines below, the galleries are very narrow to begin with, then broaden as the larvae grow.
Stigmella hemargyrella: These larvae also create a gallery mine, but the mine is most often wider and longer than that of S. tityrella, and the larvae have no issue with crossing over the leaf veins.
Parornix fagivora: This is the mine I’ve found least in my local area, though I’m not sure if that’s a reflection on the moth’s rarity or my finding skills. Look for a blister, where the larva lives at first, and then a folded leaf edge, which it inhabits a bit like a cave.
Phyllonorycter messaniella: Both Phyllonorycter species on Beech create blisters; this one is usually an oval shape, almost rectangular, and quite broad. I’ve found the upper side of the leaf can be almost featureless but the blister on the underside is quite obvious so, if recording these, it’s best to include a photo of both sides of the leaf.
Phyllonorycter maestingella: This blister mine is long and quite narrow, and often placed between leaf veins. By spinning silk, the larva draws the leaf together to create a cosy tunnel, which looks a bit like a crease on the upper side of the leaf.
I’ve attached to each of the moths’ names a link to the species description on the British Leafminers website, which is an excellent resource for anyone wanting to learn more.