Alders at Leybourne

I had another look at the Alder trees this Saturday and Sunday, looking at where the trees were on Saturday and trying to be sure of the ID features, and doing rather more on leafminers and other insects on the Sunday!

Italian Alder, Alnus cordata, is present as 3 - 4 trees on the short straight Eastern boundary, and another couple of trees on the southern edge near the houses, and another actually in the hedgeline. Rarely self-sown according to Pfaf, so perhaps planted, and (just to note) the seed requires 6 week stratification.

The leaf edges are heavily damaged by typical weevil feeding notches, of an unknown species. There was a Longhorn Caddis on one of the leaves, Mystacides longicornis, identified by Chris Brooks, after I failed to see it wasn't a moth, and posted it on i-spot! Also on the leaf can be seen the white specks of what appear to be leafhopper feeding marks, as well as what look like salt secretions.

A little further on there was a large mine which looked rather like Agromyzus alnivora, which does occur on this species. It gradually increases in width, and I think I could be persuaded that it had contained, at least at some stage, a double line of frass! So, it should be a Dipteran mine, and the only Dipteran known on Italian Alder is indeed Agromyza alnivora!

Grey Alder, Alnus incana, (L.) Moench

A few large trees on the south and east sides, with young trees underneath them. The young trees under the canopy of the older ones could well be root suckers!

Going back on the Sunday I noticed another Grey Alder, planted in the first formal hedgeline. I have walked past it a dozen times without even noticing it! A fine young tree, possibly a cultivar of the species. On the side-shoot I took for confirmation there was a whitish Phyllonorycter-type mine, similar in all respects, except in lacking a brownish colour, to Phyllonorycter strigulatella, the Grey Alder midget. That is a rare leaf-mining moth, distinctly local, and perhaps still nationally  notable. although I found it difficult to assign this one mine to any other species, perhaps it is safer to leave the ID as simply Phyllonorycter sp.

The mine was about 12 mm in length on a young still-expanding leaf, only 40 mm long.

On Sunday I think I finally concluded, from the leaf shape and shoot characteristics, that the Alder by the small pond was actually the hybrid Alnus x hybrida.

This is a possible mite gall on the hybrid Alder leaf, maybe Acalitus brevitarsus, but still to be confirmed by examining the erineum and its hairs under the microscope.

There was something feeding on this Powdery Mildew on the hybrid. Could have been a very wide range of things.