I swiped a small fly from the laundry shed wall a few nights back (I wonder how many other budding dipterists frequent laundry sheds of an evening) and tonight I finally whacked it beneath the microscope for a closer look. It was quite a weird looking thing and I was somewhat puzzled as to which family it belonged. The antennae looked decidedly Nematocera-ish, but it seemed rather a chunky monkey hence I wasn't entirely convinced. Distinctive wing shape and venation though.
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| Very well pronounced anal lobe and a distinctly S-shaped CuA2 vein |
It seemed to spill out of the key at Nematocera, confirming my initial thoughts, though definitely not a family I was familiar with. I mean, just look at those hind legs!
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| Laterally compressed but massively enlarged |
Clearly it was a male with its hugely enlarged eyes, holoptic as it's properly known, which simply means that they meet in the middle at the top of the head. Typically it's the males that have these 'over-developed' eyes, seemingly an adaptation to holding position in a single sex mating swarm whilst keeping a (large) eye out for any females attracted by the prospect of finding a suitor. I've seen this in mayflies (Ephemeroptera) but I'm not sure which other insect orders, if any, display a similar sexual dimorphism.
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| Why grandpa, what big eyes you have... |
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| Close up of wing-shape, the anal lobe and the overall rather odd wing venation |
Happily, all of this led me to a single family of flies called Simuliidae, which are the Blackflies that sometimes bite us. Or at least the females do, this is a male and its mouthparts are entirely unsuited to piercing human skin. In fact the males imbibe nectar, though I'm not sure when or where this particular chap would have last found a meal around here! I hadn't realised blackflies were quite so large, this was easily 4mm in length (which is relatively large compared to most of the flies I've been finding recently), I thought they were tiny midge-type thingies. Seems not. I'm learning - good.
Sadly, despite there being a mere 35 or so species on the British list, the Simuliidae are considered difficult to name to species, requiring both microscope slides of the genitalia and a 60-year old key that I don't currently own. It could be £15 well spent. But then again...
Simuliidae is my thirteenth PFL for the year. So quite a ways to go yet, though I'm blazing away from The Terror and The Ghost....
Right: 2 questions!
ReplyDelete1: are you using Unwin 81 to get to families?
2: are you using micro pins? If so, how the hell? I cannot use them with out losing them all over the place creating all sorts of future pain for me and mine.
I might have to catch one of the flies at the back door light to give the key a go......
Sounds like the prompt for a "how to..." blogpost. Right, I'm on it!
ReplyDeleteI'm familiar with blackflies and they can sometimes be annoying when they're prospecting exposed skin but I have never been bitten by one, even when I've stayed still and let them go for it. They look but they never bite! See if yours on Skye are just as timid.
ReplyDeleteWill do, Mark. Wish I could say the same about the midges...
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