Phyllonorycter klemannella, (Fabricius, 1781), the Dark Alder Midget
The first and possibly much the commonest mine I found today was Phyllonorycter klemanella (=kleemannella), the Dark Alder Midget. I was only looking on a few lower branches of an alder on the north side of the Bourne opposite Easterfield Bungalow.
These mines were both away from the midrib, and also close to the midrib. They showed no strong creases (so the mines were not Phyllonorycter rajella, larvae June and July), and it is the right time for the second generation of these larvae in the year, July- August. The mines were not long and thin enough to be confused with Phyllonorycter froelichiella, which is also un-creased, but with grey larvae, usually a bit later in the year, such as September-October. All these are underside mines on Common Alder, as opposed to Phyllonorycter stettinensis, which is strongly creased, characteristically yellow-green and on the topside of the leaf over a vein, larvae May and July-August but can be as late as November.
There were active green fresh mines but there were also other older mines, some emptied, which might have been from the first generation, May-June, or already-hatched mines from the second generation. Here is a supposedly typical fresh oval mine of Phyllonorycter klemanella (=kleemannella).
Here is another mine, from the upper side of the leaf.
Phyllonorycter stettinensis (Nicelli, 1852), the Small Alder Midget
I did also find two, or a few more, examples of Phyllonorycter stettinensis, on the upper side of the leaf. This is yellow green, with one strong central crease, the timing is right for the second generation but in this photograph it is NOT over a lateral vein, as described in Bladmineerders. A second mine was over a lateral vein, so that is OK!
This mine is apparently much more typical, over the vein,
Phyllonorycter froelichiella (Zeller, 1839), the Broad-barred Midget
I need to check back, but I don't seem to have ever seen froelichiella for sure - I will check through as much as I can.
.Phyllonorycter rajella (Linnaeus, 17589), the Common Alder Midget
Why haven't I found this species on the leaves of this tree? The larvae should be found in June/July and more in September/October, and I would have expected to find it by now.
Heterarthus vagans ( ),
This is a possible, but not definite, identification,