Training Toby at Leybourne

I had a shortish look around some of the mined leaves.

Phyllonorycter rajella on both Alnus glutinosa and Alnus incana (as pictured, on the underside of the leaf)

Phyllonorycter kellemanella = kleeemannella on Alnus glutinosa, one still with an active caterpillar.

Phyllonorycter stettinensis on Alnus glutinosa. The crease runs vertically up this photograph. The mine on the upperside of the leaf spills over a lateral vein.

Note how the brown discolouration has spread, but has not completely replaced the green. 

Fenusa dohrnii on Alnus glutinosa

Incurvaria pectinea on Alnus glutinosa

Agelastica alni, by golly

Walking through the pretty woodland nature reserve of Fron Wyllt, I looked at the leaves of some Alders by a small bridge over the rapidly flowing stream.

On the first day I noticed that they had been a bit frazzled.

On the second day I actually thought about it, and wondered whether they were sawfly/slugworm larvae that might be responsible. It sort of occurred to me (very slowly) that I might not have seen this damage on Alder before. It looked a little like the shredding or skeletonisation of beetle larvae damage (as I have seen regularly on Viburmum in recent years) or slugworm damage (as I have seen in the past on Birch). Eventually I found a larva which I thought I recognised as a slugworm style of sawfly larvae. A nasty-looking glossy black caterpillar.

When I got home I saw references to Alder Sawfly, but that is white and spiky, so it was not that. By chance I came across many US references to an Alder Flea Beetle with very similar larvae and blue adults. But this apparently doesn't occur in Europe. I was now intrigued and I finally came across references and photos relating to Agelastica alni, a beetle thought to be possibly extinct, but rediscovered and apparently spreading across several parts of the UK. Oddly enough, it looks very similar to the Flea Beetle from the US.

Here is a photo of a larva on apparently fresh damage, near the base of the leaf.

And another, with slightly older damage,

Here is a photo of older damage, no larva seen.

And a photo of skeletonised leaves against the sky, indicating what potential damage could be done to the Alders along our streams and rivers.

This is the site where the worst damage was seen,

Alder leafmines

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 may have found one or two examples of this leaf-miner, but it is a bit early for this particular species. Also this particular mine does look as though there is the start of a single crease in the mine, which would be unexpected in froelichiella, so maybe this is a misidentification. With this crease it could be rajella.

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,

Alders at Leybourne

I found what appears to be a third Grey Alder at Leybourne Lakes today, planted to the south side of the Round Pond.

The bark was a lovely shade of grey, although confused with various lichens.

Alder leafminers and mite galls at Haysden Country Park

Had a very short (but quite productive) hour at Haysden, where we went along the path towards the Flood Storage Barrier, looking primarily for Alder Leafminers and Galls. There were one or two fair sized Alders by the Shallows (as in the photo below) and then a good line of them along the Straight Mile. There were also a few young plants by the weir at the end of the Straight Mile. All were the Common Alder, Alnus glutinosa.

There were some Agromyza alnivora, and some galls on the leaf surface. The first I saw were small lumps scattered over the upper leaf surface, and slightly "mushroom-shaped" so might have been Eriophyes (Phytoptus) laevis. Even the galls close to the midrib were not confined to the vein axils.

The second type, further along the Straight Mile, were bumps along the midrib specifically in the vein angles, opening below, so were probably Aceria nalepai (Eriophyes inangulis). The usual leafhopper damage is also visible again.

With the Pouch Gall Acalitus brevitarsus, also seen at this site as well as at Leybourne, this brings me up to all the three mite types mentioned in Redfern and Shirley now hopefully identified.

The rusty-brown hairs on the underside of the galls were nice and clear, if a bit dark here.

Also widespread was this rust fungus, mainly on the underside of the leaves, possibly Melampsoridium alni, betulinum or hiratsukanum. M. alni is apparently only found in Asia, while M. betulinum has been noted in the UK (Scotland?) in the past, for example causing a bit of an outbreak in the 1990s. The last of these however is perhaps most likely, a newly introduced rust, since about 2000, potentially causing early defoliation and thus some economic impact on Alder species, particularly Alnus incana.

Going back to the Leafminers, here is what might be the top surface indications of Phyllonorycter kleemannella = klemannella, the Dark Alder Midget, nominally at least small, oval and often away from the midrib. The larvae are supposedly found in May/June and July/August, quite a lot earlier than this particular record, but the Dutch suggest there may be \a third generation increasingly recently.

This "cutout" might have been caused by an earlier leafminer scar that has dropped completely out, and if so, the long and thin shape suggests that it might have been Phyllonorycter froelichiella, the Broad-barred Midget. There are other possibilities though, and even kleemannella = klemannella can be long and thin and look like froelichiella....

As well as probable Aceria nalepai galls, this leaf might just be showing a leaf-mine of Caloptilia falconipenella, as it is right on the margin of the leaf and shows a bit of turning over of the margin. This moth is however nationally scarce B, so the mine might be of something else.

Alder Leafminers at Leybourne.

A successful visit this afternoon, with a reasonable good variety of leaf-mines found, concentrating entirely on Alder. Plenty of birds around, Blue Tits, Coots, Moorhen, Cormorants, Great Crested Grebes.

I concentrated mainly on Common Alder, Alnus glutinosa, but I was also able to spend some time on the Italian Alder, Alnus cordifolia and the Grey Alder, Alnus incana .

One of the really enjoyable finds was one mine of Heterarthus vagans on one of the large Italian Alders at the southern edge of The Ocean. The pupation disc was really nice and obvious, and gives us the possible opportunity of rearing the pupa through to adulthood. I have found this species once before at Leybourne, earlier this month  - although that time I had it down as on Common Alder, when found on the 19th September. It is known to occur on both species.

Another excitement was my first sighting (as far as I know) of Phyllonorycter stettinensis, the only Phyllonorycter to be found on the upperside of Alder leaves. This was seen on Common Alder. The appearance of this Phyllonorycter was noticeably different to the normal matt colours of those on the underside of the leaves - the P. stettinensis mine is a glossy light green, then turning brown. The mine is often over a vein, and may be quite strongly creased.

Another species I could recognise was Phyllonorycter rajella, with its strong crease on the surface of the mine, close to the midrib of the leaf.

More difficult to be sure of were the relatively uncreased oval mines on the underside of the leaves close to or away from the midrib, which I would imagine were mainly Phyllonorycter kleemaniella - but difficult to separate clearly from Phyllonorycter froelichiella, which is also oval and uncreased, but longer, normally over 25 mm long.

Here is a fairly reasonable picture of what I think is a reasonably early (and active) stage of the sawfly mine Fenusa dohrnii in an Italian Alder leaf. It was towards the upper side of the leaf, with frass tending to gather in the centre of the mine (as in one of the Blaadmineerders photos for example), and "spilt out" over a major vein towards the margin of the leaf, as noted for this species. There was only one mine in this particular leaf, but most other factors seemed to fit, and it is a relatively common mine.

The larva takes about three weeks to complete its mine, and then pupates outside, eventually becoming a tiny (c. 4 mm.), mainly black, sawfly. At the moment this mine is relatively translucent and has not yet developed the opaque mid-brown colour, often in the end highly crinkled, of the mine to be seen in its later stages.

Slightly less exciting than some of the other leafminers were reasonable numbers of the usually common Agromyza alnivora, the only fly miner found on Alder species in the UK to my knowledge.

Alder leafmines at Leybourne Lakes

I thought I came across a few Caloptilia falconipennela "leaf-edge folds" throughout the Common Alders on the southern side of "The Ocean".


Near the causeway I found a few more mines - including this possible identification of the moth caterpillar Phyllonorycter kleemannella = klemannella (The Dark Alder Midget). The season is only right-ish (mines are supposedly found in May/June and July/August with a possible third generation) but it is supposed to be a common species, and it cannot really be anything else! The caterpillar is supposed to attack the Common, Grey and Italian Alders in the UK, but not the Green Alder. This is a rather poor picture of the mine on the underside of the leaf, not very large, and certainly not extending the majority of the distance between midrib and leaf margin. Just visible near the top are three small creases?

and these pictures are of the larva extricated from the above mine, which is pale and typical of all the Phyllonorycter species except Phyllonorycter froelichiella, where the larva is grey. Once the larva pupates it is found in a white cocoon attached to the roof of the mine, well away from the frass piled in a corner. Before emergence the pupa wriggles to be partly sticking out of the mine, ready to emerge!

and the sawfly Heterarthus vagans on Common Alder, Alnus glutinosa. This common sawfly caterpillar is supposed to attack the Common, Grey and Italian Alders in the UK, but not the Green Alder.

This is probably the pre-pupal stage of Heterarthus vagans, extricated from an apparent pupation disc of the large brown mine of rather indeterminate shape. There appeared to be several discs on the leaf, but actually only one live insect. However the guides suggest that there is normally only one mine per leaf.