Not quite as terrifyingly horrific as disembarking from a landing craft and straight into heavy enemy gunfire, as happened early one June morning in 1944 (I'm sure you've seen the Omaha Beach landing scenes from Saving Private Ryan) but nonetheless, after viewing this down the barrel of my microscope, I felt a sudden pang of sympathy for the hapless victims of the beetle I found scampering across the grass clipping pile this morning. Imagine you are a centimetre long, quietly squirming your way through the grass heap before sensing you were being watched. You freeze, trying to escape notice but already it's far too late as you are scooped up into the jaws of death...
Pity one mandible moved inwards a smidge before the glue dried
Beetles have very definitely taken a back seat of late. In fact, I was pondering that sad fact just this morning, wondering what it would take to reignite my interest in them. And then boom - this huge bugger ran out in front of me, right on cue.
Safely in a glass pot - barely!
I was in the process of dumping my second or third wheelie bin of grass clippings onto a rather sizeable grass heap when I spotted motion by my foot. Ooh, a great big brown staphy. I had no pots or tubes on me - instant panic! I reached down and grabbed it in my fist before heading indoors to find a tube. There's a fair chance that had I have noticed quite how large its jaws were I may have acted differently! Anyway, I threw it into a large glass tube and was shocked to watch it scamper up the vertical sides with ease. Twice I almost decapitated it whilst trying to slam the lid into place, but finally it was contained within and I continued emptying and refilling the wheelie bin with yet more grass clippings. Those lawns were getting a tad out of control but it's great to know that the resulting grass piles are proving so attractive to flies and their predators.
As soon as I'd finished for the day, I looked to see exactly what it was that I'd captured.
This is Ontholestes tessellatus, a large staphylinid beetle that can be found in dung heaps, carrion and also - it would seem - in and around decomposing grass clipping piles. Basically, anywhere that has a concentration of fly and beetle larva upon which it preys. I've not seen this beetle before. There are just two British species in the genus, the other being Ontholestes murinus which I've seen before, though not on Skye. Ontholestes tessellatus is my 529th British beetle. One day I shall attempt to work out how many of those 529 were self-found and identified. I fear far too many have been shown to me without my understanding quite why they were what I was told at the time.
It really is a spectacular beast! The NBN Atlas suggests it is entirely new to Skye (indeed new to the whole of The Hebrides), but Richard Moore lists two records from adjacent Raasay, though none for Skye itself.
This is a fast-moving killing machine, pouncing on its victims from above. There's only one song that fits. Enjoy!
This is the famous Taxis to Hell – and Back – Into the Jaws of Deathphotograph, taken on June 6th 1944 by Robert F. Sargent, a chief photographer's mate in the United States Coast Guard. It shows the ill fated beach landing by American troops, landing on an unexpectedly heavily fortified beach held by a well-entrenched German army. After huge losses on both sides, the beach was finally taken.
I know what you're thinking, no posts for weeks on end and then two on the same day! What can I say - maybe I should take a day off more often. Please do feel free to petition my boss demanding that henceforth I only work a two day week. Obviously without any drop in pay.
So, alongside yesterday's pipunculid lifer, I spotted an intriguing-looking fly sat on a bracken frond. I watched it from afar (ie from about a metre away, wondering if it would vanish before I unlimbered my net and handle from my rucksack and quickly assembled them) before remembering I had a camera in my pocket. This was the single shot I took before swiping the hastily assembled net into action and securing my quarry in a small glass tube.
The epitome of a 'record shot'
I then stood still and took a thorough visual scan across the surrounding bracken fronds. It was soon obvious to me that, at any given moment, I could see at least two or three of these mystery flies wherever I looked. I potted up a second individual, this also from a bracken frond, before heading off in search of warm sunlit spots.
My initial thought was that these were maybe sciomyzids; they had that sort of flat, broad-winged, short-legged look to them. Back indoors I ran them through Oosterbroek and was delighted (yes delighted!) to key them through to Opomyzidae, a whole new dipteran family for me! Even better, there aren't very many of them on the British list and I just happened to have a chart of wing patterns and a key to species already saved on my desktop - sweet!
The wing pattern, combined with tergite colour, is enough to clinch the species
Basal scutellar bristles much the same length as the apical scutellar bristles
No vibrissae, a single recurved F-bristle, scattered setulae between the eyes...
This is Opomyza germinationis, which is apparently one of the commonest flies in Britain. Opomyza petrei is the main confusion species, but there are differences in tergite colouring and patterning and the ovipositor differs between species (both of my examples were female). NBN shows a whole barrage of Philip Entwhistle records from the far south-east of Skye and I fully expect it to occur in almost any patch of woodland edge throughout the island.
Opomyzidae is my 48th dipteran family of the year, 36 of which have seen me identify at least one specimen to species level. The remaining dozen are either exceedingly difficult/obscure or I lack the required keys/magnification/skill level. All told, I have now seen and recognised members from 53 British dipteran families, which equates to 49.5% of the 107 families that occur here. One more and I'm halfway there!
In case you were wondering, the 2020 Challenge between myself and The Ghost is still ongoing. Neither of us has been furloughed and we've both been busy at work and otherwise. In fact, I've been substantially busier than usual at work ever since the Covid-enforced shutdown of the hotel. But I've still managed to get out and play from time to time.
Yesterday was my ninth consecutive day at work. I deliberately finished up by 3:30pm and hit the woods whilst the sun was shining (today, my one day off, it is raining. Exactly as was forecast...) Happily, I found a few interesting wee things yesterday afternoon including one fly that immediately grabbed my attention as it slowly floated beneath some bracken, legs dangling and wings catching the light very nicely indeed. One swipe of the net and it was captured.
Why Grandma, what big eyes you have! (And you appear to have a stinger too...)
This is one of the Big-headed Flies (Pipunculidae), closely related to the Hoverflies (Syrphidae), in fact these two families compose the superfamily Syrphoidea. I guess the term 'Big-headed Fly' is a bit non-PC these days, but hoverflies do hover and big-headed flies do have rather a big head, so....
Pipunculids have a bit of a reputation as being proper hard bastards to key correctly. A lot of this is due to earlier works not recognising species aggregates, something that is now far better understood, though work does still need to be done in some areas. Taxonomically there have been a good few changes since my copy of the RES Key was published in 1966. This key is still available to buy as a used hardcopy (mine has annotations in the margins) but this online version is far more readily available and is free to download. In this key there are 77 species described as British, a massive jump from Verrall's 1901 work which recognised 32 species.
Dave Gibbs, possibly Britain's greatest pan-species lister, runs the Pipunculidae Study Group which has distribution maps for each British species and keys to genera. Nowadays there are 95 species of pipunculids on the British list. To quote Dave from his site -
...with the exception of a few very conspicuous species, all these records have been checked by me. Because of the considerable difficulty most people encounter with these flies, I have not accepted records unseen.
Dave is a professional dipterist, hence his maps can be considered overwhelmingly accurate. I currently have a handful of pipunculids on pins, all collected from here on Skye. Once their flight season is over I shall post them off to Dave for confirmation (or re-determination) and get a few more dots added to his atlas. Skye seems relatively devoid of 'pips' judging from the maps, with just 7 species recorded up here. I strongly suspect that this is entirely down to observer bias - all of the Skye records are clustered in the far south-eastern region, an area which was heavily frequented by a renowned entomologist whilst holidaying on Skye.
Happy that I was looking at a pipunculid, I set about keying it to species with my battered 1966 RES key. First was the key to subfamily, which I'll run through in an abridged fashion.
Couplet 1 - are there ocellar bristles?
You can see the three small ocelli situated on a small bump between the rear edges of the eyes. No bristles visible from above or from the side. So far so good, go to Couplet 3...
Couplet 3 - is the hind margin of the eye deeply excised and do the thorax and scutellum have strong marginal bristles?
Clearly there is no strong excision in the hind margin of the eyes and, although the scutellum has strong marginal bristles, the thorax does not. Which takes us to couplet 4 (Pipunculinae)
Couplet 4 - Coloured or colourless stigma?
The stigma definitely has a bit of brownish colour to it, which leads us to couplet 6.
Couplet 6 - Tricky one this, though you wouldn't think so from reading the key. Thorax universally (though minutely) hairy on top, or with two lines of (tiny) dorsocentral hairs and bare between? This is where I've gone wrong before when keying pipunculids. The hairs are almost invisible from most angles, but once you know what you're looking for they are fairly easy to see. Not so easy to photograph though!
This was the best of a bad bunch of images! Hopefully you can see the two rows of pale hairs running back along the top of the thorax, just along the outer edge of each pale band. Helpfully, the microscope's ring light has illuminated the tips of these hairs making them easier to discern. Onwards to couplet 7.
Couplet 7 - Propleural fan of hairs present or absent? This is a bit of a bugger to see and all but impossible to photograph without removing the head, and I didn't want to remove the head. This may be a bit of a leap of faith for you, so just take my word and believe me when I say there's a propleural fan of hairs visible in this next image!
So what you're looking at here is the back of an eye. Beneath the silver-coloured rim are lots of small downward/inward-pointing, essentially straight hairs that are directed into the cavity behind the huge eye and are facing towards the front of the thorax. These are easy enough to see. But, if you squint really hard, you should be able to make out a bunch of curved hairs coming from the depths of the shadow and curving from right to left. This is the propleural fan. In the image below I've highlighted this fan in coloured ink. A very young schoolkid could do better, I know, but at least it'll give you a head's up of what to look for in the image above.
All of which has finally led us to a subfamily - Cephalops. Phew!
There are quite a few Cephalops in the 1966 RES Key. Thankfully, this specimen drops out to species very early in the couplets.
Couplet 1 - Vein M1+2 with or without an appendix of varying length?
No messing around there, that's a very definite appendix! Previously, I had a specimen with a tiny appendix along this vein (and on both wings too) which can occasionally happen in aberrant specimens. If I ignored the appendix it keyed through nicely to what I hope is the correct species. If I ran it through the keys as having an appendix - which is what I did first time around - it makes a nonsense and goes nowhere. Anyway, appendix present on this specimen - go to couplet 2.
Couplet 2 - a very long couplet filled with lots of detail which leads to one species, or alternatively lots of detail which leads to another species. Different set of details for males and females. This is a female (it has a wicked-looking ovipositor). Essentially it all comes down to colour of the tergites when viewed from above and the shape of the ovipositor. So...
"Tergites 2 to 4 are light grey, sometimes black or brown banded anteriorly, when this colour may also extend across the disc of the thorax".
"Base of ovipositor fairly deep, with an apical large brown protuberance above which appears rounded from side view"
All of which, miracle of miracles, would seem to lead to a straightforward identity! My fly is a female Cephalops furcatus. Unfortunately that name is no longer in use, my fly has now been redesignated as Cephalosphaera furcata. A quick glance at Dave's distribution map for this species shows it to occur northwards as far as central Scotland, making this is a notable record as it rather extends the currently known distribution.
In other good news, I whacked the image up on the UK Diptera Facebook group and it was 'Liked' and commented upon by several decent dipterists, which is far better than the "I think you may have gone wrong with this one" type comment that I so often see.
