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.

Lullingstone and leafminers with a start to a personal key

Anne and I added ourselves onto The Ash Project's basic tree identification course run by Mike Phillips run at Lullingstone this morning. I came across some Alder mines, at least one of which that fitted Phyllonorycter rajella fairly well from its shape, position and single strong crease, a mine that I don't think I have found elsewhere yet, so very pleasing to see.

Lullingstone is a fairly dry site, and the Alders I was looking at were in the (probably) deliberately planted shaws running uphill from the visitor centre. These seem popular feeding spots with the migrating swallows and martins by the way.

The mines were on the underside of the leaf, close to the midrib and with a single strong crease running longitudinally along the mine. There was one fresh, and several slightly older mines, one of which exactly fitted rajella. The distinguishing feature of the strong crease was new to me, despite the apparent commonness of the species, the Common Alder Midget. The mine is sometimes described as triangular but it may extend further across the leaf making it more rectangular (picture in Eakring Birds). There were several other mines, and although none were entirely diagnostic, any of the three underside species could have been there.

Personal Key to Common Alder Phyllonorycter species 

All these are between the veins on the underside of the leaf,

Near the midribnormally, maybe triangular, single strong crease, Mines in June-July, and again September - October, common: rajella (Lullingstone, Mote Park). Larvae green, if found.

Short, a few weak creases perhaps, June-July, September - October, common: klemannella (Leybourne, Bourne, Mote Park). This is by far the commonest in my limited experience. The larva, if ever found, should be generally quite pale and also rather obviously yellow in the middle sections.

Long, near full half-width of leaf, uncreased, September - October, common: froelichiella. The larva should be grey, if found.


This one, however, is on the upperside of the leaf

Maybe between, maybe over, a vein, with a strong crease, July, and again in October, "common"; stettinensis. UK Moths has: "it forms a small oval mine on the upper leaf surface, with a crease down the centre. Unlike other species that form an upperside mine, the surface is not papery, but quite glossy and heavily creased. The mine begins green and then turns orange or brown when more mature." Wikipedia has that "the frass is deposited in a corner of the mine".  


Grey Alder

Generally similar to Common Alder, except that the long mine of froelichiella is replaced by a different long mine, that of a nationally notable species, strigulatella.


Italian Alder

A restricted list, consisting of just the two fairly shortish species: strongly creased rajella and the only weakly creased klemannella.



One of the Stigmella species was found as well on the Common Alder.

There were also old galls which were probably formed by Acalitus brevitarsus, pouches extending above the leafblade, with now rusty coloured hairs beneath.

Sorbus at Lower Halstow

Unknown Stigmella on the Sorbus outside Judy's house at Lapwing Close, could have been S. magdalenae.

The Hucking Estate

Interesting to see the number of Hornbeam within the older woods, and the very few young Hornbeams in the newer plantings.

Phyllonorycter

On the Hornbeams in the older (ASN?) Woods there seems to be a lot of "caterpillar" style damage in the interior of the woods, leaving very tattered leaves indeed. There was also Phyllonorycter esperella on the upperside of the leaves, both remnant signs of the first generation of mines, and newer mines, some starting to bend the leaves up as they tighten (by the way, how physically DO they tighten?). Some of these appeared to have already left their mines. On the underside of the leaves could be seen long narrow mines, strongly narrowed by the contraction of the mines, with clear single creases running along their mid-lines, possibly Phyllonorycter tenerella. There might have been some Phyllonorycter messaniella mines as well.

Stigmella

There were a few Stigmella mines, probably caused by Stigmella microtheriella from their tendency to follow the leaf veins, but Stigmella floslactella may well have been there as well. One mine seemed particularly broader, a feature I believe more associated with Stigmella carpinella. Again, no signs of the hoped for Bucculatrix, Coleophora, Paracrania or Parornix style mines on this site so far.

Aceria

I did find the apparently common gall mites, Aceria tenella, that live in colonies within hairy "spots", each one in one of the leaf axils. Here is a close up showing the reddish-brown discolouration of the hairs induced by the mite in the axil below the midrib - compare this with the relatively tiny clump of whitish hairs in the normal leaf axil above the midrib just to the right. It is also worth noting the very long whitish hairs of the plant lying along the midrib - what on earth can they be for?

Getting muddier in Dene Park

Looked at some other leaves for leaf miners today, but also got a snap (with flash) of Phyllonorycter esperella on the upperside of a Hornbeam leaf, just starting to pull the leaf up as it tightens.

Dene Park, 26.09.2017

I also saw a mine possibly created by Parornix carpinella, which would make it a new mine for me!

I had a quick look at a few Beech leaves, and spotted an old friend, Stigmella tityrella, which I have seen both at Dene Park, and also at Bod Petrual near Ruthin. Not a very good photo I am afraid! Notice the browning to the side of the mine itself.

Hornbeam leafminers at Dene Park.

Had a lovely walk in Dene Park with Monty, taking a moderately careful look for Hornbeam leafmines. The weather was slightly cool, but nice and sunny - a lovely early autumn day.

None of the fairly accessible and easy to find Stigmella mines from today seemed particularly fresh, so I assume are from the June-July activity. This reduces the accuracy of the ID from species to genus, but almost all the mines seemed fairly thin and had some tendency to follow the leaf veins or midrib for at least part of their activity, so the best of my guesses would be Stigmella microtheriella, one of the two commoner species, and the one noted for following veins. The frass pattern has apparently deteriorated over time, so is now less useful for diagnosis I would say, and there were no larvae present to examine. The remaining frass pattern did appear to be restricted to the centre of the mine as opposed to filling the full width of the mine. However there is another quite likely possibility, Stigmella floslactella, which is equally thin, but rather less tendency for following the leaf veins, and where the frass width initially fills the early stage of the mine. The critical distinguishing feature is the relative thickness of the frass to mine diameter in the early stages. Both species could well be present!

On a few of the smaller leaves there were some notably white mines, which did seem significantly broader and much more convoluted - there is some minor possibility that they were Stigmella carpinella, a rarer mine in the UK, and not specifically noted to be in Kent on the UK Flymines site. There was no frass and there were no larvae to check, so these must remain entirely uncertain, especially as even David Gardiner's 2010 records were not validated.

Dene Park, 22.09.2017

It will be interesting to wait for the September - October activity, if it isn't there already, to see if diagnosis is any the easier slightly later in the year!

There were also some Phyllonorycter types, some on the underside between the veins, and some (more rounded usually) on the upperside centred above one or more principal veins.

Some of the ones on the underside could perhaps be Phyllonorycter tenerella and if so they should have a fairly strong single crease, and extend from midrib to leaf edge, or nearly so. None I saw completely filled these criteria, but none were fresh, so that might be the explanation. Others could be either Phyllonorycter messaniella (which may also have one strong crease, perhaps forked at the end) or Phyllonorycter ulmifoliella (which may have more and smaller creases), both of which are apparently less extended in length.

This old mine below is on the underside, bounded clearly by the veins, but not long enough to be typical P. tenerella, leaving one of the other two as the most likely candidates for this and the great majority of the underside mines seen on this site. However ulmifoliella is rarely mentioned apart from the UK leafminers site, and although this would indicate that messaniella is the most likely species by a short head, all options must remain open. ACTUALLY this is a mine of Stigmella possibly microtheriella that has "cut out" an oblong of leaf with its travels.

(I went back on Sunday, the 24th, and this time found two possibly fresher mines on the underside of the leaves - oval, but loose, between the veins, about half the distance between midrib and leaf edge, apparently empty, with no visible creases, neither single nor multiple. Therefore I was no further forward - except the continuing gut feeling that the mines are not tenerella, because they are too short).

The leafmine frequently found on the upperside of the leaf is much easier as it is the only upperside Phyllonorycter listed, and so keys out on UK Leafminers as Phyllonorycter esperella (Goeze, 1783), a leafminer specific to Hornbeam in the UK. This species, the adult moth of which is known as the Dark Hornbeam Midget, also occurs throughout mid to southern Europe across to the Near East, and as well as the Hornbeam, it also attacks the Hop Hornbeam, Ostrya carpinifolia where that tree occurs abroad.

This I think is a very common mine in Kent, and I generally find it whenever I look carefully at Hornbeam leaves in woodland, or even quite urban trees (e.g. Hadlow College). I am fairly sure I also saw some in Ryarsh Wood last week. The ones I saw today were generally quite young, relatively small and oval, over the centre of a principal vein. These larvae will have come from eggs laid by the second generation of adult moths, which were on the wing in August.

This one however (the only one found like this) is probably an older mine of this species, demonstrating the upward folding of the leaf as the tentiform mine ages and tightens.

I didn't see any sign of an Eriocraniid type mine today, a long splodgy mine on the edge of a leaf. Eriocrania chrysolepidella is also known as Paracrania chrysolepidella. I was surprised not to find it, given its apparent reasonably widespread (ukflymines) if local (uk leafminers) coverage in the UK, and some existing East Kent records. Nor did I find any Parornix or Bucculatrix mines.

A slow, very relaxed walk, and Monty had a lovely time breaking up sticks in the mud.

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.