Saturday, 2 January 2021

Moth Highlights 2020

2020. To use a mothing analogy, you travelled a long way to get to a great site for a really rare moth that you’d been looking forward to seeing for ages. The traps went on at dusk, full of anticipation, and then March came in, the rain started, the MV bulb got wet and exploded. Somehow despite the bulb being out Hornets still descended en masse and ate all the moths you had caught, and then set about you, and after you’d extricated yourself from all that mess, it turned out you had the wrong grid reference and had been trapping in the wrong place anyway, plus the consolation rarity you thought you’d caught needed gen det anyway, and you didn’t retain it.

Despite all that, 2020 was a really enjoyable moth year for me, and in spite of lockdowns and travel restrictions, I managed to catch up with an exciting variety of new moths. The mothing year basically started when I returned to ancestral Somerset for the first lockdown in March. As the season got going, I was unable to get out and do the usual spring butterfly stuff, and so I turned to micros in the local lanes and woods. Highlights here were three rather under-recorded Coleophoras – solitariella and lithargyrinella as larval cases, and Metroites lutarea as an adult, all on Greater Stitchwort along the lanes near home.

Stichwort-feeding Coleophora habitat in West Somerset

Coleophora solitariella larva
Metrioties lutarea doing what it does best

Coleophora lithargyrinella case

I also spent a fair bit of time up at a nearby forestry commission site, where there are some good stands of Broom clinging to the path edges as the serried ranks of Sitka Spruce advance. I found a number of new species for me feeding on this, including Mirificarma mulinella, Anarsia spartiella and Agonopterix assimilella. None of them blockbuster rarities, but really satisfying to see some of the characteristic species of this moth-rich shrub. As a bonus, while harassing it with a beating tray in the vain hope of Streak larvae I dislodged a couple of Epinotia fraternana (presumably from the nearby spruce plantation), the third record for Somerset. 

Mirificarma mulinella larva

Epinotia fraternana

As restrictions eased, it was finally time to enact plans hatched over the winter to see a few new species, and my first proper trip out was on a classic May morning to a site near Porlock to look for the semi-legendary Schiffermuellerina grandis. It must have one of the most extravagant binomials of any UK micro, but unlike Brown House Moth (Hofmannophila pseudopretella!), it feels totally appropriate, this Oecophorid is a stunning mish-mash of yellow, silver and electric blue, and a bit of a rarity. For a while it was thought to only persist at a few sites in Somerset and Devon, but it's recently been re-discovered in the New Forest and the Wyre Forest. I was pleased to find it flying in numbers in the morning sun (between 8:00 and 10:00), textbook stuff. I saw just over 20 in the end, with little leks in sunny openings, and the males dancing to and fro like giant shiny midges.

The mythic Schiffermuellerina grandis

In a suitably mysterious setting too

Nearby, at Hurlstone Point on the same day, I came across a large patch of Sheep’s Bit growing in one of the coastal combes, giving me the chance to enact another winter plan. Having received Brian Hancock’s excellent ‘Pug Moths of North West Britain’ for Christmas last year, I was determined to be a bit more serious about pugs, and so returned at the end of May to trap at Hurlstone in the hope of Netted and Thyme Pugs, and perhaps Jasione in among that Sheep’s Bit. 

Sheep's Bit in what later turned out to be Jasione Pug country at Hurlstone Point

It was my first evening of proper field trapping, and an ausipcious start - Nightjars churred over the heathland, the waves broke in Porlock bay, and the fishermen murmured to each other on the shingle below. The moths performed too – 2 each of Netted and Thyme Pugs, lots of Barrett’s Marbled Coronet (and Marbled Coronet), Horse Chestnut, Galium Carpet, Grass Emerald, and best of all 2 Jasione Pugs (inevitably not arriving at the trap set among the Sheep’s Bit). These were the 2nd for VC5 (and the first for over 100 years) of a moth that seems to be rather rarely-recorded recently, as it seems quite shy about coming to light. I later found it in the same area as a larva in August, the traditional way of recording it. A random micro potted off the same trap as the pugs was also sent off for gen det with Paul Wilkins, and came back as Denisia subaquilea – a first for Somerset. This species seems to occur quite widely on moorland up north, but is only previously known from Devon and Cornwall down south, where it frequents the same maritime heath/coastal grassland as Jasione Pug.

Netted Pug

Jasione Pug - Hurlstone Point

Jasione Pug larva - Hurlstone Point

Pugs continued to be a feature of 2020, with a couple of others to raise the pulse back in Oxfordshire when restrictions eased. A wonderful session trapping at Aston Rowant in July yielded a whole host of chalk grassland specialists, among which was a superb fresh Pimpinel Pug. Like Jasione Pug, this is a rather shy one that doesn’t appear at light often, being more easily recorded as a larva on Burnet Saxifrage in September (when I had expected to be looking for it), and this was the first for Oxfordshire since the 80s.

Pimpinel Pug

Aston Rowant also provided a nice pug larva too, in the form of a Netted Pug hiding in a Bladder Campion seed head near the entrance to the site, while I also managed to find Valerian Pug larvae at a number of sites around Oxford (some of them with only small patches of the foodplant – seems to be one to look out for wherever it occurs).

Netted Pug larva lurking in a Bladder Campion seedhead at Aston Rowant

Valerian Pug larva

Alongside the pugs, another group that featured heavily this year was the plumes, again making good idle threats made in my round-up of 2019 highlights, to enact the teachings of another well-chosen Christmas gift, Colin Hart’s Plume moths of Britain. Back in Somerset in the spring, I spent a lot of time at the crumbling cliffs at Watchet, where I found two really nice plumes. After failing to find anything other than one extremely dead and almost unidentifiable larva, Goldenrod Plume proved to be common by day around all the larger patches of its foodplant on the cliffs. This is a rather rare beast (nationally scarce A) and absolutely stunning - some illustrations make it look a bit lake a fancy Triangle Plume, but it’s something else entirely in the flesh with its wonderful ermine trim. I also found a few Wood Sage Plume larvae here, in their characteristic wilted shoots, the second for VC5. The plume book wryly comments that larvae found at this stage are often parasitized, and indeed it proved so.

Goldenrod Plume

Wood Sage Plume larva

Another second plume for VC5 was the red-data book Horehound Plume. Its foodplant, White Horehound, is itself a rather scarce thing, only known from 4 areas of Somerset. I realised the moth had only been recorded from 3 of these, and headed to the last, some rather parched limestone grassland near Bridgwater. On arrival I was greeted by some good stands of the rather ghostly foodplant, liberally scattered with high densities of both adult and larval Horehound Plumes, resting on the leaves in the boiling afternoon sun.

White Horehound in Horehound Plume country

Horehound Plume larva

Horehound Plume

After these, the plumes kept coming, and I recorded a total of 15 species over the year. Another highlight was the diminutive Sundew Plume in Devon and Somerset. As its name suggests, this remarkable moth turns the tables on the insectivorous sundews, and the larva feeds on the leaves, licking the secretions off the sticky hairs that normally act as a trap for invertebrates, munching said hairs, and then setting about the leaf itself.

Sundew Plume

While down in Somerset, I managed one other trip out trapping, returning once more to the cliffs at Watchet. It was a cool night, but delivered a nice variety of hoped-for limestone specialists, many of which were new to me, including Pretty Chalk Carpet, Fern, and best of all more Thyme Pugs (for my money one of the prettiest of the group – with those bluish tones), the second Sand Dart for VC5, and Maple Prominent, a moth I had long failed to see (despite living just on the edge of its weird little Somerset outpost). By day the cliffs also provided further excitement – Narrow-Bordered Bee Hawks seemed to have a good year, and I had nice views of females thundering around the slumps and egg-laying on Devil’s Bit Scabious, while a nice little colony of Scythris picaepennis also revealed itself, the first for VC5.

Thyme Pug

Narrow-Bordered Bee Hawk egg-laying

Goldenrod Plume habitat

Scythris picaepennis

Another night time expedition to the coast came in late May, when I decided I was so starved of excitement by travel restrictions that a night time search for Scarce Blackneck larvae on Exmoor would be a good idea. After tramping out to the remote beach where it was last recorded in Somerset (in 2003), I stomped about in the darkness for a couple of hours, completely failing to even find any Wood Vetch (its foodplant) at the grid references I had, let alone any larvae. With my resolve failing, I tried heading away from my grid reference, and about a kilometre of pebbles later, I found the plant and found the larvae. 5 of them to be precise. Munching away quite happily out in the open at 11:30pm.

Scarce Blackneck larva

Scarce Blackneck larva

Back in Oxford, my solo field trapping was limited to three trips out, of which two were at Aston Rowant. The first was at Sydlings Copse, where after trekking across the fields, traps in hand, I managed to get wet from both above and below, choosing to trap in the very soggy fen, in the hope of Dentated Pug, on a decidedly rainy night. Dentated Pug of course did not show, and nor could larvae be found in September, but I got a nice variety of wetland species for my efforts. The two sessions trapping at Aston Rowant were rather more successful, with 100+ species on both nights. As well as the afore-mentioned Pimpinel Pug, other excitement was provided by a large selection of chalk grassland specialists, including Sitochroa palealis, Chalk Carpet, Oncocera semirubella, Parectopa ononidis, Barred Rivulet, Citron Plume, Coleophora lixella, Festoon and Hypochalcia ahenella. Top billing went to Coleophora niveicostella (pRDB3, a rather scarce Thyme Feeder and the 3rd for Oxfordshire) and Argresthia abdominalis. This Juniper feeder is pRDB2, and doesn’t seem to have taken advantage of garden plants, being restricted to wild Junipers on chalk downland. It is therefore very rare, and this was the second Oxfordshire record, the last having been in 1974… at Aston Rowant. It was caught on my second trapping trip on the reserve, a fantastically atmospheric night in August, right on the top of Linky Down, from where I could sit and watch the traffic roaring down from London on the M40, lightning flashing in the distance, and the Juniper Pugs busy fluttering around the foodplant egg-laying, all on a night that didn’t get below 20c the whole time I was there.

Argyresthia abdominalis

Coleophora niveicostella


Parectopa ononidis

Aston Rowant also delivered excitement by day, including adults of the lovely little Nemophora minimella and the mines of Ectoedemia arcuatella on Wild Strawberry – the second and first records (respectively) of these species for Oxfordshire.

Nemophora minimella (male)

Ectoedemia arcuatella mine

Over the latter half of the summer, I found 2 more new moths for Oxfordshire as leafmines. Most cryptic was Phyllonorycter ulicicolella, rooted out of a gorse spine at Sydlings Copse in November, while more expected was Lyonetia prunifoliella which has been expanding its range and threatening to make an entrance for a while, duly doing so with some mines on Blackthorn along the Thames at Goring. About half an hour before finding these, I’d also potted a Sorhagenia sp. Off some Buckthorn and thought very little of it, other than that it was my first of this genus, and rather rare, but on going under Peter Hall’s knife it turned out to be janiszewskae, and another new moth for Oxfordshire. All of this was found on a trip that failed to find Epermenia insecurella at nearby Hartslock. In mothing, it seems best to expect the unexpected.

Phyllonorycter ulicicolella mine - Sydlings Copse

Lyonetia prunifoliella mine - Goring

Further local excitement was provided by a session leaf-mining up at Wytham Woods with Doug Boyes, where we found Phyllocnistis xenia (Grey Poplar) and Cosmopterix scribaiella (Reed), which (pending verification of 2019 records) look like they might be new to VC22.

Phyllocnistis xenia mine

Cosmopterix scribaiella mines

Leaf-mining has continued right up to the present day as well, at the start of December, scrabbling around on Putney Bridge and embarrassing some friends as I collected Pellitory of the Wall covered in Cosmopterix pulchrimella mines, and also with several winter trips to look for miners on gorse and broom. After the initial success at Sydlings Copse, I spent quite a bit more time looking for the mines of Phyllonorycter ulicicolella, and its close relative, scopariella. I found the former at 3 more sites, and the latter at 2, including back in native Somerset at Willet Hill, where it was new to VC5. There’s a bit more about searching for these in an older post on this blog.

Cosmopterix pulchrimella - ex mine on Putney Bridge

Phyllonorycter scopariella mine - Greenham Common

In numbers, 2020 was my best year for moths yet, I recorded 746 species in total, in contrast to 617 in 2019. Of these, 220 were new for me, taking me past my 1000th species (a Tissue at Aston Rowant apparently). Interestingly, in 2019, 161 of these were not at light, whereas in 2020 it was 322 – a marked shift in approach as being stationed in a city full-time deprived me of garden trapping, and I tried to be a bit more targeted about tracking down rare species by day (77 vs 56 nationally notable species in 2019). In a year marked by a dramatic shrinking of social horizons, it was also nice that some of my mothing managed to be a bit more collaborative than 2019 (or rather exploitative, as it was mostly other people generously helping me), and I owe a big thanks to people who helped with with IDs (particularly Rob Edmunds, Peter Hall and Paul Wilkins), queries (the long-suffering Somerset/Upper Thames recorders) and let me tag along with trapping trips (big thanks to Doug Boyes and the hundreds of species he showed me up at Wytham), as well as the people who generously let me trap on their land (the National Trust in Somerset, and BBOWT and Natural England in Oxfordshire).

Monday, 28 December 2020

Finding Phyllonorycter ulicicolella and scopariella

In an effort to stave off the winter mothing/butterflying blues that has arguably only led to further suffering, I've spent quite a bit of time over the last few weeks looking for leaf mines on Gorse and Broom. Each plant has a Phyllonorycter species (and broom has a few extra miners of which more later) that makes very subtle mines inside the stems (or leaves/spikes on Gorse) - Phyllonorycter ulicicolella on Gorse, and scopariella on Broom. The unobtrusive nature of these mines, and the fact they're probably easiest to look for during the winter (when most sensible folk are dissecting things and sorting their records for the year) means that they're not recorded very often. In fact, unlike almost all other leafminers in the UK, both species seem to be recorded more often as adults, typically beaten from the foodplant, rather than as mines. Like most leafminers though, they're probably both very under-recorded and waiting to be found at new sites. This has certainly been my experience in the last few weeks. Because lockdown has given me very little else to do, I've now found the mines of ulicicolella at 4 sites, and scopariella at 2. Two of these finds were new for their vice-counties (ulicicolella in VC23 - Oxfordshire, and scopariella in VC5 - South Somerset). All of the sites were new as well, and some of them didn't have loads of the foodplant (and much of it wasn't in great condition), so I'm sure they're lurking out there at lots of new sites, like most leafminers.

In order to justify the hours expended on searching for these two miners, I thought I'd try and put all my photos of them and their habitat together into this blog post in the hope that it also helps others thinking of looking for them develop a bit of a search image by looking at lots of pictures first, before heading out into the field. It should be cautioned that my total count of mines of each species is now about 40 for ulicicolella, and 20ish for scopariella, which is hardly huge, so any generalisations about what kind of plants they like, how variable the mines are etc ought to be taken with a healthy pinch of salt.

What habitat?

I've searched for the mines of ulicicolella at 5 sites now, and found them at 4 of these. The first was Sydlings Copse (Oxon), a very small fragment of rather degraded sandy heath, then Bagley Woods (Oxon, but VC22) not so sandy, just small amounts of gorse growing along the edge of the wood. Next was Greenham Common (Berks) rather stony heathland (acres upon acres of gorse), and finally Willet Hill (Somerset) where small amounts of rather unhappy gorse plants grow along the edges of Sitka spruce plantations, it's stony and rather acid on the soil front here. Phyllonorycter scopariella was then also found at Greenham Common (not loads of Broom here, I searched about 40 plants) and Willet Hill (rather less Broom, a lot of which has been damaged and removed by forestry operations, probably about 20 searchable plants but more being choked in plantations). I think the only take home here is that these sites don't have loads in common geologically or habitat-wise, they just have the foodplants, but in very variable amounts and condition.

Which plants?

With such a small sample of mines (and a not very systematic approach to searching), it's hard to say whether each species has a preference. One thing that it clear is that pretty much all the mines of ulicicolella that I have found have (I think!) been on Western Gorse rather than Common Gorse. Similarly, they seem to prefer the slightly bushier, older growth rather than the young fast-growing stuff (at the tops of bushes, or growing as suckers) that has very large spines. Virtually all the mines I've found have been on the stems of such growth, and not on the spines as some people have found them (I've only found one like this, the first one at Sydlings Copse). This growth seems to be more common on slightly scraggly, older, woody plants (as side shoots off the woody stems), and the highest densities of mines that I've found have been on rather old and unhappy looking plants. Edit: That said, I saw on twitter that it's been found on younger gorse in Gloucestershire recently, and after publishing this blog I saw Jack Oughton's excellent pictures of mines on much younger, thicker growth down in Devon this winter. Edit 2: on 07/03/21 I visited Frilford Heath golf course (in Oxfordshire, but Berkshire for moth recording) where there's a small amount of gorse has been retained, seemingly for an aesthetic finish to the course. I sought out scraggly-looking bushes of the kind where I had found mines before, and checked 3 that I thought looked good. All of them had mines on (8, 7 and 4 respectively).

A rather crude representation of the kind of growth where I've found
most ulicicolella mines.It's not super obvious here, but hopefully
the photos of the actual mines get the point across too.

This gorse bush had 8 mines of Phyllonorycter ulicicolella on - 
Greenham Common (Berkshire)

This very unhappy gorse bush lurking under a willow by the track at Willet Hill (Somerset)
had at least 15 ulicicolella mines on it.

A late addition to this blog after I first wrote it -
this scraggly bush at Frilford Heath
(Berkshire/Oxfordshire) had 8 mines on it.

Another leggy bush from Frilford Heath with 7 mines on

Some wider context  of an ulicicolella site - the small patch
of gorse retained at Frilford Heath golf course. The 6 broom bushes in
the corner of the picture also had mines of Trifurcula immundella.

Having said all that, I'm not sure whether this means ulicicolella has a real preference for these kinds of plants, or they're just much easier to detect on them, when the spikes are small and sparse, and the stems aren't too dense. This is probably why I've found so few mines on the much more densely spiked western gorse. 

As for scopariella, I think the sample is probably too small to say anything really specific. I have found no mines on young suckering broom though, and again, the highest densities have been on slightly larger, older plants. I've found them on some very battered ones too, that have been chopped and damaged by forestry in Somerset.

I found about ten mines of scopariella on this old Broom
being squashed by a spruce plantation at Willet Hill (Somerset)

This rather battered Broom on the edge of a forestry track had two mines of scopariella on - Willet Hill (Somerset)

Two for the price of one: the gorse on the right and the broom on the left here both had their respective Phyllonorycters in residence - Willet Hill (Somerset)

The mines in the field

Phyllonorycter ulicicolella is a very tricky mine to spot, showing just as an area of paler green on the stem, often (but seemingly not always) with some purpley-brown bruising. How strong these features are seems to really vary, and some mines are much more obvious than others. In a couple of instances I've spotted one nice clear mine, and then noticed others next to it while taking pictures.

Two Phyllonorycter ulicicolella mines - Willet Hill (Somerset)

Three ulicicolella mines from the same bush -
Willet Hill (Somerset)

This single very large and obvious ulicicolella mine was on the
same bush as well - Willet Hill (Somerset)

A rather subtle ulicicolella mine - Willet Hill (Somerset)

and a more obvious one on the same bush

I think scopariella is rather easier to pick out, look for an area of uniform discolouration on the broom stem, wrapping round it and continuing up the stem. Initially they seem to be greyish and slightly inflated, before fading to brown and then whitish on very old mines. These old mines are the most obvious, and the ones I've felt happiest recording, as I think some of the greyer specimens of the young mines can look a little like Trifurcula immundella mines (these are basically black, and don't fade to white or anything, unlike scopariella).

Two old scopariella mines at the base of some Broom side-shoots -
Willet Hill (Somerset)

An old scopariella mine on a side-shoot - Willet Hill (Somerset)

The mines up close

There's not much to say about the mines up close that hasn't been stated above, but here are some pictures of them that hopefully demonstrate the features already mentioned, and how they vary.

ulicicolella - Willet Hill (Somerset)

A nice obvious ulicicolella - Bagley Woods (Oxfordshire/Berkshire)

ulicicolella - Greenham Common (Berkshire)

Two ulicicolella mines - Greenham Common (Berkshire)

An ulicicolella mine with strong purple bruising - Greenham Common (Berkshire)

ulicicolella - Greenham Common (Berkshire)

The first ulicicolella mine, and the only one I've found on a spike - 
Sydlings Copse (Oxfordshire)

ulicicolella - Willet Hill (Somerset)

scopariella - Willet Hill (Somerset)

scopariella - Willet Hill (Somerset)

scopariella - Greenham Common (Berkshire)

The same scopariella mine, but from a different angle, showing the 
oldest part of the mine that has faded more - Greenham Common (Berkshire)

Confirming the ID

I don't think I'd want to record either species without opening up a putative mine to check that there is/has been a larva in it (and it's not just some similar-looking damage) by opening it up to look inside. It seems to be okay to record these species without a larva, and just the frass, as nothing else seems to mine in the same way. Opening up the mines so that you can see the contents is tricky for ulicicolella. I initially tried pulling off spikes, and then peeling them back so they stripped away the upper layers of the stem, or using a knife to do the same thing, but I found they removed too much of the stem, often taking the upper layers that contained the larva and any frass. The technique I'm trying now is to 'unzip' the mine rather than peel its top off, by just cutting down the middle of it, either just using a nail or the tip of a sharp knife (I imagine a needle might work as well). This technique seems to work well for scopariella mines too, which are a bit more hollow and split down the middle nicely. Phyllonorycter ulicolella seems to have quite distinctive pale orange-yellow frass that fades to red-brown with age, while the few scopariella mines I've opened up have been quite old and had rather dark frass. 

ulicicolella - the frass is initially quite yellowy as here
(Willet Hill, Somerset)

It gets darker with age though (Sydlings Copse, Oxfordshire)

scopariella - Greenham Common (Berkshire)

scopariella - Willet Hill (Somerset)

I've struggled to find the larvae in the mines, and have only found 5 ulicolella larvae in the mines I've opened up (though I haven't always opened them fully), and no scopariella. The ulicolella larva is quite a weird looking one, being rather long and slim, and was only recently formally described in the entomological literature by Rob Edmunds a few years ago (2005, Ent Rec vol 117, part 4).

Phyllonorycter ulicicolella larva - Willet Hill (Somerset)

A larva in the mine - Frilford Heath Golf Course (Oxfordshire/Berkshire)

Other stuff to look out for

If you're searching over the winter, there are a couple of other things on Broom to keep an eye out for too. Fristly, two miners - Trifurcula immundella and Leucoptera spartifoliella both make linear, blackish mines along the stems. I've only found the former, which can be told from spartifoliella by the distinctive egg case at the end of the mine. I think I may have overlooked spartifoliella, as you still need to open up mines that don't have the egg shell to check the larva (and make sure it's not just an immundella mine on which the egg has fallen off), and I don't normally do this if I've been finding lots of immundella mines (which seem to be quite ubiquitous).

Trifurcula immundella mine, with the distinctive egg in an inset - 
Bagley Woods (Oxfordshire/Berkshire)

There's also an Agonopterix species that feeds over the winter - assimilella, in a spinning between branches, usually obvious thanks to protruding white silk. Again, caution is needed here, as the dreaded Light Brown Apple Moth can also be found in a similar spinning. 

These three species are all described and illustrated in a bit more detail here (along with a nice young scopariella mine), in a handy blog post from Tony Davis. They’re also all featured in Ben Smart’s excellent Micro Moth Field Tips book, and of course, all the miners mentioned here are pictured on Rob Edmunds’ leaf-miner website (to whom a big thanks for confirming the IDs of many of the mines featured here). Later in the year, in spring, there are lots of other things to look out for on Broom, several more Agonopterix species, Anarsia spartiella, Mirificarma mulinella, and the larvae of the Streak can all be found (or not, in the case of the latter on my patch). It's a plant well worth paying close attention to in all seasons.