The Humbling River

Just downhill from here lies Uig Wood, with a block of native 'Celtic Rainforest' woodland heading upstream of the road and a 130 year old planted woodland dominating the downstream side of the same road. The upstream section has a footpath that dead-ends after just a few hundred feet at the remains of a weir (dynamited apart in the 1930s by a person with a grudge to bear, apparently!) Unlike the busy downstream section, this upper section enjoys far fewer visitors. I like it, it gives me the opportunity to act like a complete insect geek in public, all in relative safety and anonymity.

The river has been running high for much of the year thus far, thanks to an extremely extended wet period, but it has now finally subsided somewhat. Subsided to the point that I can safely explore the backwaters and pools for diving beetles without the need for chest waders, a sturdy rope and an emergency whistle.

Now you may call me childish or simple-minded (and honestly I don't mind), but I find it absolutely captivating to quietly watch diving beetles swimming around underwater as though they own the place. Which in their world they clearly do. One genus in particular would appear to be quite common in the river; Oreodytes. These are small diving beetles, closely related to the far larger Dytiscus diving beetles that many folks are familiar with. There are only four members of the genus known to occur in Britain, Oreodytes alpinus, davisii, sanmarkii and septentrionalis. O.alpinus is a curiosity in Britain, known only from the far north eastern corner of Scotland and presumed to be a relict species left over from the last Ice Age. It's also the only member of the genus I've yet to encounter. 

A couple of days back I found myself at the edge of a shallow pool, watching a couple of Oreodytes swimming across the surface of algae-laden stones, I managed to hook one out without too much difficulty. Back indoors I soon had it carded and ready for identification

Pity it has lost an antenna

This is Oreodytes sanmarkii, a species that I've found here before. And here is the other species of Oreodytes that I've found in this river

A very poorly carded specimen, I know this...

I must have been in some sort of a tearing rush when I carded this beetle, it's appalling! I need to find another and set it out properly. This is Oreodytes davisii, which, at 3.8 - 4.5mm, is more elongated and somewhat larger than the commoner Oreodytes sanmarkii (2.9 - 3.3mm). 

Here's a pic of them side by side

My carding technique is definitely improving...

That's a pretty obvious size difference when shown side by side! I've recorded Oreodytes septentrionalis only once before, with Mark Telfer at Loch Garten last year. Mark retained and determined the specimen, hence I'm keen to find and determine my own at some point. Plus I'd really like to get up to that top corner of Scotland and see if I can locate Oreodytes alpinus for myself. 

I haven't listened to this track for a good few months, YouTube tells me it now has something to do with the soundtrack to a Transformers film, which is pretty gutting. Anyway, if you don't know it, this is Puscifer with their sublime track The Humbling River

An Early Season Muscid

It was nice and sunny today and, out of the cool wind, it was modestly warm too. I quickly headed into Uig Wood in search of flies sunning themselves on tree trunks and within ten minutes I'd potted up four sizeable muscids, all of which looked to be the same species. A brief bout of sweeping low vegetation added several very small flies to my tally, all of which I brought indoors to pin and identify. But first the four muscids.

They were all from the genus Phaonia and I used this key to take them to species level. There are almost 50 species of Phaonia in Britain, though not all of them occur this far north, whilst others only fly later in the year. This particular key is very user-friendly and is well illustrated throughout, indeed it was almost a joy to work through.

The key is in two parts, the first for males and the second for female flies. I had three males and one female and they all keyed through very nicely. 

Male Phaonia have eyes which almost meet in the middle of the head, females have eyes that are widely separated from each other, as shown here

The underside of the abdomen differs between the sexes too. Males exhibit a horseshoe-shaped feature which houses the genitalia and the end of the abdomen is broadly rounded. In the females this feature is narrower and far more elongated and the abdomen itself has a more pointed profile

Right, so now we are ready to identify our first fly. I chose a male and began keying. 

Couplet 1 - is the underside of the scutellum bare or is there a patch of fine hairs?

No hairs under there - it's completely bare

Couplet 2 regards the length of the hairs on the arista, are they short, very short, or longer than the diameter of the widest part of the arista? This was easy to see but a complete pig to photograph! 

You're looking at the antenna which has a thick "bristle" projecting from it. This "bristle" is the arista and you'll see small hairs radiating from it, almost creating the impression of a feather. It's the length of these small hairs that we need to be checking. Clearly they are wider than the diameter of the arista at its widest part, which takes us to...

Couplet 3 - which asks whether the radio-cubital node has bristles or not. I forgot to take a photo of this, but it was bare. You'll just have to take my word for that. That leads us on to...

Couplet 5 -  now we need to look at certain bristles on the top of the fly's thorax. Bristles and hairs cover much of a fly's body and each 'tract' of bristles has a term unique to it. Sometimes even an individual bristle has its own name, as does each part of the body where they occur. It's quite boggling, but entirely necessary in order to determine that you are looking at the correct set of bristles. Anyway...

Does the area in front of the suture have 1+ pairs of acrostichals, or none? I've added coloured dots to the image below. In this instance the acrostichals are coloured BLUE. The suture is the thin line that runs across the width of the fly's back, BLUE dots on one side of it and RED dots on the other.

Clearly there are acrostichals in the area before the suture, which leads us to...

Couplet 31 (that's a pleasing jump, we're really getting somewhere now!) - there are a few parts to this couplet leading to just two choices, but essentially it breaks down to this:  

1) is the underside of the abdomen entirely translucent yellowish or is it black?  

2) Are there 4 dorsocentrals or not?

3) Are the sides of the scutellum hairy or bare beneath the strong bristles?

1) We can see from the images above that the abdomen is yellowish not black - easy.

2) The dorsocentrals are a series of bristles that form a line running along the top of the thorax, approximately halfway between the midline and the sides. In the image above I've marked them with RED dots. Clearly there are four of them.

3) Check the images above and below. The scutellum is the rounded pad between the wing bases. It's attached to the fly's back but has its own set of named bristles and hairs. In this instance we're interested in the strong marginal bristles, each of which I've marked with a RED dot in the image below

No hairs below those bristles - the sides are completely bare

So we have a yellow underside to the abdomen, 4 dorsocentrals and bare sides to the scutellum, which is the option that takes us to....

Couplet 32 - 1 pair of presutural acrostichals and an entirely reddish-yellow scutellum OR 2-3 pairs of presutural acrostichals and the scutellum broadly darkened at the base. The presutural acrostichals are marked with BLUE dots (see two images above), the scutellum is the image directly above. The second option fits our fly which takes us onwards to....

Couplet 33 - Another multi-part couplet leading to just two options 

1) arista scarcely as wide as antennal segment or distinctly wider? We've already looked at the arista back at Couplet 2 and you can see that, including the fine outstanding hairs, it is not quite as wide as the antennal segment it arises from. Definitely not "distinctly wider", at least.  

2) Middle tibia with 2 or with 3 posterior bristles? All flies have bristles on their legs and, being flies, all of these bristles have different names and positions. The posterior ones are obviously the ones on the back of the leg facing the direction behind the fly.

Two posterior bristles on the middle tibia

The third and final part of this couplet is a bit confusing and it took me a minute to figure out exactly what it was that the key was asking me to look at. But it's very obvious once the penny drops! 

3) Seen from behind, the median pair of presutural dark thoracic stripes, level with the first dorsocentral, is quite two thirds of the width of the grey dusted stripe separating them, OR not more than one third the width of the grey dusted stripe separating them. Clear???

Go back up the screen three images, to the one where I've added the coloured dots. This time look at the ORANGE dots. These mark the first dorsocentral bristle (edit - I've just noticed that the upper orange dot is at the wrong bristle - oops!) Between these orange dots is a series of black and grey stripes. The couplet wants to know if the middle two black stripes are two thirds the width of the central grey stripe or less than one third the width of the grey stripe. I reckon they are definitely over half the width, thus I favour the two thirds option over the barely one third option. 

All of which...wait for it...drops us out at a species: "Phaonia subventa - Very common and generally distributed; often emerges during the winter in dwellings". Very common it may well be, but it's the first time I've identified it! The other two males ran through the exact same route and dropped out at Phaonia subventa. The female fly too, with all couplets being identical to those in the male key apart from the last one where the black stripes are narrower, half the width rather than two thirds the width. It fitted and it too is Phaonia subventa.  

What a beauty! 

Sieving Chainsaw Dust

Last autumn, two large Wych Elms were pollarded in the hotel grounds. Long story short - the logs were sectioned into metre lengths, several months later (about 2 weeks ago) a guy turned up and chainsawed them into shorter lengths so that I could load them onto my logsplitter and reduce them to firewood-sized chunks. I did a day's worth of splitting last week, today I finished splitting the sawn stuff. The fella with the chainsaw ran out of fuel on the day, there's still an awful lot of laying timber that needs to be sectioned and split, but who knows when he'll be coming back now.

Very nearly done!

You'll have to excuse the horrible metal bin in the background. It's one of those commercial 1280 litre galvanised things, I simply removed the wheels and lid and converted it into a firepit (coz everyone loves a good burn up!) The stuff I've leaned up against the wall has still to be chained to length, each lump is about 3 to 4 feet long, I need it cut into about ten inch lengths. As you can see, a fair amount of chainsaw dust has accumulated on the ground. You'll notice that some of it is still lovely and damp, I figured it would be worth sieving for staphs and who knows what else!

Just because I'm quite impressed by how much wood I split today, here's a video I took afterwards. This doesn't include the stuff split earlier - that's already been stacked into the woodshed. Note the shovel handle at the end, I wondered where it had gone! 

Anyway, I collected a large bucketful of debris and then managed to persuade the head chef that it was perfectly acceptable to nab his largest sieve for the purposes of sifting sawdust for beetles. We've had our moments in the past, but he's a good chap really. I suspect he thinks I'm quite mad. Here's the set up

A nice alternative use of the staff smoking shelter that I built last year

I think it took me about an hour and a half to satisfy myself that I'd gleaned every beetle from that bucket of sawdust. I have to say, there wasn't an awful lot to show for it afterwards, but that's not entirely unexpected.

Firstly the logs were only sawn in March. It's been cold ever since, hence most beetles have been largely dormant. The few that have been active have only had a few weeks to locate the mound of sawdust, though I did find several larvae, so clearly something is breeding in there. I suspect that when the rest of the logs are chainsawed to length, presumably sometime in the summer, there will be a far larger influx of beetles. Time will tell. 

This is what I managed to sieve from that bucket of sawdust

 This is how they appeared a short while later

I undertook yet another botched ptilid gen. det. - bloody things! Transmitted light via my compound revealed nothing. I removed the abdomen, micro-pinned it into place and began carefully opening it up. Bugger all. Sheesh, clearly I'm doing something wrong! You can see in the image above that I resorted to whacking them all on the same card. The 'large' beetles on the right of the image weigh in at 5mm. The featherwings come in at approximately half a smidge above zero mm....

Anyway, I now have more beetles to play around with. Aside from the featherwings, a single Cartodere nodifer is the sole non-staphylinid in this collection. One is an aleocharine, that gets put aside for another time. The remainder seem to comprise just three species. I shall get back to you regards their IDs. I also grabbed a couple of larvae, I do after all own a copy of the RES key to beetle larvae so may as well see how well it works. I suspect Staphylinidae.

Edit: the breakdown of beetles sieved from the bucket is as follows
Proteinus brachypterus x3
Cartodere nodifer x1
Omalium rugatum x2
Dimetrota atramentaria x3 (lifer!)
4 featherwings, 1 smashed beyond all recognition, the other 3 still to be determined....
1 very small aleocharine not even attempted
The two larvae are staphylinids as initially suspected

Lonchoptera lutea

I swept a small fly last week and finally got around to identifying it a couple of evenings back. I say 'small', but it's actually quite a bit larger than much of the stuff I've been looking at recently. Here it is alongside my finger and thumb for scale

Huge booger!

It has a very distinctive wing shape and venation, I knew exactly from which family it belonged. Here's a closer look, taken down the barrel of my microscope

This is from the family Lonchopteridae, know as the 'Spear-winged Flies'. There are only seven species on the British list and, despite being quite small, they aren't too tricky a bunch to identify. There's a brilliant online key which you can view and download here.

Working through the key necessitates a close look at the legs and a tiny row of spines along a wing vein, but it's all quite simple as long as you have a microscope. I think you'd definitely struggle with just a handlens. 

The red dots are my additions

The wing venation is diagnostic; all of the cross-veins are restricted to the basal area which, combined with the elongated wing shape (some might even say spear-shaped!), tells us we're dealing with Lonchopteridae. You'll notice that 'm' (the media vein) forks by the upper red dot. The lower red dot marks where 'a1' (anal vein 1) reaches the wing margin. In this instance they more or less line up with each other. Options in the key are that vein a1 ends "far beyond", "beyond", "at most only slightly beyond", or "rarely ending much beyond" the level of the fork. What are your thoughts?

Another thing to look at are the bristles on the fore tibia, where are they situated and how many of them are there?

Again, the red dots are my additions

Flies are covered in various hairs and bristles, each of which are uniquely named in order to distinguish them from all of the other hairs and bristles that occur on other parts of the body. The body itself is split into a great many named parts, and each vein in the wing is also named. All in all, there are a very great many bodyparts, veins and bristles of which to keep track! The terminology is truly bizarre and often confusing, but it certainly does help you to recognise the various 'bits' the keys require you to check. 

Vertical bristles and postocular cilliation all pale

Happily, my fly was a male so after working my way through the key, I came out to a species that seemed to match. Then all I had to do was compare its genitalia to the diagram to ensure I had it right, as no two fly species in a genus will have the same shaped genitalia - this essentially stops them mating with the wrong species. Imagine a lock and key, try to put the wrong key in the lock and it just won't open up. 

Male genitalia as viewed from the underside once I'd unhinged it

Looks a pretty good match to me

So what we have is a male Lonchoptera lutea, a common fly that I've seen here before. I also found a Lonchoptera bifurcata walking across a tree trunk the week before I swept this one from grass. Two down, five to go! Sadly they don't all occur this far north. 

I wonder if there are any fly families out there where all family members occur on Skye..?

A quick tour

A short while back I changed the card in my camera and now I can't find the full up one that I cunningly hid somewhere in my room. So, despite there being a backlog of some three weeks from the last blogpost, I don't have very many images to show you! 

Luckily I'd already shifted a few onto my desktop, including several showing specific locations I intended to target for fly and beetle searches. Then lockdown happened. To be fair, they are all in my home 1km square and I am allowed out once per day for 'exercise'. I'm not sure swinging a net and sieving piles of woodchip was quite what the government were thinking of when they defined exercise, so I shall try to restrict any such activities to when I'm well out of sight of any members of the public (not tricky around here!)

So here's a very short virtual tour of some hotspots for you....

This was a rather substantial Sycamore until recently, will soon be full of great beetles!

These large fallen logs are an absolute magnet for sunbathing flies

Again, the lichen-encrusted rocks in this wall are a magnet for sunbathing flies

Still to find Norellia spinipes on any daffodils this far north - not for lack of trying though!

There was a solitary sallow at the end of this lane that put forth good numbers of catkins. I was banking on this tree to provide me with a run of interesting flies and beetles. Sadly, the council foiled that plot and all that remains is a six inch high stump and a thin carpet of woodchip. At least they could have heaped the chippings instead of spreading it around. Or left the tree alone, actually!

I took myself for a wander over a nearby hill last week, the sun was out and I couldn't stand to just stare at the world through the window. Sunny but very chilly and my attempt at finding a sheltered suntrap found me staring at a windswept Ivy hang with buggerall on it. I spent a short while sweeping over the low grasses beneath trees high above the River Conon. Lots of ticks (the arachnids I mean, not lifers) and this assortment of flies, mirids and a bunch of Stenus for my efforts

Currently lounging in a small Backlog Box...

The fungus gnat Mycetophila ornata

EDIT - these are neither beetles or flies. My bad!

    

I bought myself an LED ring light for my microscope, I honestly have no idea how I got by with my desk lamp beforehand. £25 well spent, just check out the difference!

Euophryum confine viewed down the barrel of my microscope as lit by the desk lamp

Ta da!!!! Same beast, same set up, but illuminated by the ring light rather than the desk lamp

I'm pretty pleased with the extra level of detail I can discern with the LED set up. For features requiring low side lighting I can revert back to the desk lamp, it's right next to the microscope anyway so no hassle there. The LEDs are dimmable, from very bright to barely visible and the camera sensors deal with the light source a lot better too, colours are now much truer to life. The only downside is the reflection bouncing back from the insect itself, as can be seen on the pronotum above. But basically a sound purchase, in my opinion.

The only other thing of note was finding my first Cantharis soldier beetle of the year, though not quite how I'd been anticipating the occasion

Taken just before it fell to the woodland floor, never to be seen again! 

I'm now at 93 species of beetle identified from 22 families (plus an extra two families where I haven't identified the specimens to species level) and 28 species of fly identified from 17 families (plus an extra 11 families where I haven't identified the specimens to species level). 

Not sure where The Ghost is at regards his beetle family tally, but he's certainly behind me for flies, though I fully expect that to change any day now. Mark is hot on my heels regards number of diptera families he's recorded so far this year. As for the beetles? Sheesh, who even  knows! He's probably just waiting for the final four or five families to fall and that'll be him done for the year... I'm really out of my depth here, but it's still fun. 

For now. 

Time to Split

Today was my final day with The Ghost, he's a truly remarkable chap and a damn fine friend of mine. I'm heading west next, just for an over-nighter, before shooting back up to Skye and reality once more. 

The Ghost searching for Dwarf Sedge...in the wrong area

This was at Martin Down NNR earlier today, a site which, somewhat surprisingly, I've never visited before. After successfully locating Dwarf Sedge we ambled back across the downs noting a few nice beetles. It was still far too chilly for flies, despite the bright sunlight.

Lesser Bloody-nosed Beetles doing that thing they always seem to be doing

Exapion ulicis - we found dozens of these clambering around flowering gorse

We also found a couple of Pine Ladybirds emerging from their overwintering sites deep in a gorse thicket

We both realised that, despite the glorious sunshine, the cold wind was suppressing any fly activity. If only we could find a sheltered suntrap somewhere... We headed off for nearby woodland but The Ghost had his own cunning plan involving a pair of secateurs and some nettles. We drove southwards a bit more and ended up someplace deep in the Test Valley.

Despite us now having shelter from the wind, it was still pretty darned chilly. No flies at all (other than a small cloud of dancing Trichocera) were in evidence. So we hit the nettlebed bigtime. Our targets were the stoutest stems of last year's nettle growth. The Ghost was using his secateurs, I just ripped the stems out with my bare hands, trying hard not to make gratuitous 'raaaarrr' noises in the process. I've never split so many nettle stems in my life, I even broke a nail before eventually remembering the penknife in my pocket. 

I'll let you have a brief ponder as to why we were splitting last year's nettle stems. Here's a pic to distract you whilst you have a think

Chromatomyia scolopendra (Agromyzidae) mine on Hart's-tongue Fern

The Ghost had remembered something that I'd completely forgotten about - the fact that I had yet to encounter either of the agromyzids that bore through the centre of nettle stems. Luckily (for me, at least) it didn't take him too long to find this small larva inside a nettle stem. 

This is Phytomyza flavicornis - and a lifer for me!

Pretty soon though, we were finding another species of dipteran larvae in nettle stems. And then shedloads more inside Hogweed stems, sometimes two or three together. This mystery species had obviously blackened rear spiracles with a small spike on each, quite unlike the small pale bulbs of Phytomyza flavicornis. Neither of us knew what they were, so we collected a load to rear through.

I collected seven, I think The Ghost collected about ten

  

Back indoors we did a bit of online research. Before too long I'd figured what it was that we had discovered.

Phytomyza flavicornis - note the diagnostically shaped cephalic skeleton

The three pale, rounded 'bulbs' at the rear end of the Phytomyza flavicornis larva

And now for the second species...

Black chitinised spiracles, located very close together and with a sharp 'thorn' surrounded by distinct papillae

Substantially larger than the Phytomyza flavicornis larva

It was Melanagromyza angeliciphaga, new for both of us. Sweet, I like unexpected bonus species.

We had a quick tally up of our respective 2020 Vision totals. The Ghost has 22 named species (12 flies and 10 beetles) and I have 22 flies and 89 beetles. So it's a close thing thus far...

Just wait until he gets into the thick of it when the flies finally emerge, I won't see him for dust. This ridiculous lead is not going to last long, I just know it!

February Round-up

So that's me completed the second month of my 2020 Vision Challenge and I know exactly what you're thinking - was February any better for me than January was (could it really be any worse?)

At the end of January I'd managed to find and identify just ten species of beetle and eleven species of fly. That's poor, very poor. I realise that January doesn't exactly offer the best opportunities for finding insects, especially not up on Skye, but I really was hoping for more.

Luckily for me, come mid-February, I managed to skive a whole three weeks off work and immediately headed south to meet up with The Ghost and Mark Telfer, both of whom pulled out the stops to ensure we all spent quality time in the field (and Whipsnade Zoo's hot house!) Sadly the weather was still pretty crap; wet, cold and windy being the norm. Even the brighter days were still cold, hence I didn't add very much in the way of dipteran interest. The beetles were pretty good though. 

Chromatomyia scolopendri on Hart's-tongue Fern - the pupa is visible in the mine

And if you think that is scraping the barrel....

Time flies like an arrow, fruit flies like a banana

This was from inside the butterfly house at Whipsnade Zoo. Despite being abundant over the heaps of rotting bananas left out for the butterflies, they were a complete bugger to catch (I hadn't brought my butterfly net into the butterfly house - I figured that would be pushing my luck too far). I haven't gotten around to even attempting to ID the fruit flies yet, though Drosophilidae was an unexpected family tick for the year. Coz yep, I'll take anything to stay ahead of The Ghost, though I fear I'll be at the back of the pack soon enough, once spring arrives. 

I took the opportunity to take my fungus gnat haul to BENHS at Dinton just in case fungus gnat guru Peter Chandler was in attendance. Guess what...

Get in!!!!

Sadly I only had two species (out of twelve specimens) but he's happy for me to send him more specimens near the end of the year for the national recording scheme that he runs. Hence I'll hopefully glean a few more for the tally. The other good news is that I now recognise the diagnostic wing patterning of Mycetophila ornata, so I don't have to collect any more of those. 

Beetles came thick and fast, many species from a small patch of reedbed flood debris, yet more from a couple of decent leaf-litter sieving sessions in South Hampshire. One that particularly surprised me was this beast

Paederus littoralis - high up on a calcareous hillside!

Previously I've only ever seen Paederus in wetland habitats and the name littoralis would suggest this is a shoreline species. Except I was halfway up Magdalen Hill Downs near Winchester. However, the mandibles don't lie (they were black) and it transpires that Paederus littoralis is just as happy in dry habitats as wet. Cool, a very smart lifer too.

Speaking of lifers, I accumulated quite a few during February. A very meagre total of just three new flies, but a somewhat healthier seventeen new beetles. The 2020 Challenge totals at the close of February stand at 17 species of Diptera and 46 species of Coleoptera. As a sneak preview, the start of March was pretty magical for beetles. So I better hurry up and blog about that too.