Post details: Check out this massive fly


Check out this massive fly
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This weekend The Ranger discovered that the biggest fly in the UK was much bigger than he'd previously thought. Yes, we heard you wanted to see a picture of a simply gigantic horsefly. So here it is.

Tabanus sudeticus (c) Cat James

This is Tabanus sudeticus, sometimes called the dark giant horsefly. It seems, oddly enough, that this impressive insect has not really got a commonly-accepted English name. It's referred to in one place as the "dark behemothic horsefly": a charmingly descriptive name, albeit a little cumbersome.

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Yes, it's sitting on my finger and no it didn't bite me. They can be up to 25mm long (that's one inch) and 50mm across the wings - a massive fly and the largest dipteran in Europe (I think it was bigger! Having measured the Ranger's finger, the fly could've been at least 30mm - The Cat).

Horseflies are big, fast-flying creatures, and they will bite any big mammal, including humans. The bite is very painful, and as horseflies cut the skin when they bite (rather than pierce it), horsefly bites can take a long time to heal, and can cause infection. Unlike insects which surreptitiously puncture the skin with needle-like organs, horse flies have mandibles like tiny serrated scimitars, which they use to rip and slice flesh apart. So I'm quite glad my new friend didn't take a nibble out of me. Given the size of it, it might have left me rather drained and anaemic.

I was walking in a wet meadow in West Hampshire, where the thick, lush vegetation was buzzing with life. Swallows swooped overhead, and we were admiring the bee-flys that seemed to be almost swarming around us. Suddenly, my companion Cat shuddered to a halt having nearly trodden on what she at first thought to be a moth. It turned out to be the biggest fly we had ever seen. It was soon captive in a jamjar and being admired safely through glass. In the video above a 5p coin is in the jar for scale.

Tabanus sudeticus (c) Cat James

Adult horse flies feed on nectar and sometimes pollen, and the female flies drink a blood meal before laying eggs. Males don't drink blood - so which is this character? The key is in the eyes. Like many big-eyed dipterans, the males have holoptic eyes which meet in the middle, whereas the females have a bar separating the two big eyes. Clearly, in the picture you can see that this one is a female. Mmm. Good job she wasn't hungry.

After a bit of cooing and gawping; we decided to let the captive free, as she seemed to be getting a little irritated by her imprisonment. It shook itself, cleaned itself for a moment, and flew off with a noise that sounded more like the low drone of a stag beetle or moth than the buzz of a fly.

We'll report the sighting the the Hants fly recorder in due course as the species is not very widely distributed. One would imagine that any sightings would be quite often noted, as the things are so spectacular.

Anyway, we didn't have a saddle that would fit it, otherwise we might have tried to ride it home.

12 comments so far, see them and add yours here!

Posted on 7th June 2009 at 4 24 pm
by The Virtual Ranger
2969 views

Categories: Wildlife & countryside news and comment
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Comments:

Comment from: The Wildlife Gardener Email
Ew! You're braver than me to handle it. Great pics!
PermalinkPermalink 07/06/09 @ 18:10

 

Comment from: Richard Email · http://honesthypocrite.blogspot.com/
Wow.

The eyes are really huge and you can see the opalescence due to their multifacetedness. My natural philosopher interests would have been completely overwhelmed by my running away instincts.
PermalinkPermalink 07/06/09 @ 20:41

 

Comment from: Steve Email · http://kingsdownkent.blogspot.com/
What a brute - looking at the map I'm pleased to see that they don't menace Kent, but I can see a dot in Devon where I was bitten a few years ago - memorably painful!
PermalinkPermalink 07/06/09 @ 22:08

 

Comment from: Rambling Rob Email · http://wightrambler.blogspot.com
Valiant research - thanks for the warning!
PermalinkPermalink 08/06/09 @ 11:45

 

Comment from: Woolumstick Email
So glad I didn't handle the one that I just ducked to avoid that flew into the shed 10 minutes ago and then caught in a container and took a couple of pics of. A beast at about 2.5cm long. Thanks for your research - hope I never see one again! From sunny Devon :D
PermalinkPermalink 29/06/09 @ 16:44

 

Comment from: Lee Email
I've just seen one of these in my rural Dumfriesshire garden...the first I ever saw...thought it was a kind of large wasp first then looked again and searched for it on the net. Think it was a male,about 30mm long. I am quite used to a large variety of unusual bugs and biting insects here being on the fringe of forest and grazing land.
PermalinkPermalink 05/07/09 @ 09:58

 

Comment from: James Email
Just last night, we had one of these in our bathroom. The window had been open all day and it was walking along the sill.

We're in Cumbria on the south coast 2 miles from the sea. It was gigantic, quite an impressive thing. I have spent hours trying to identify it and am very chuffed to have come across thing page! Finally! Great site!
PermalinkPermalink 08/07/09 @ 12:46

 

Comment from: Mark Kessell Email
Found one of these on the front door step of our house in West Wales. It was huge. As an engineer i'm quite good at estimating size and this thing was easily 40mm long. Took a photo of it against a £1 coin for scale. Impressive beastie.
PermalinkPermalink 10/07/09 @ 09:04

 

Excellent pictures above, I took one recently of a gigantic specimen, albeit through a window of a camper van, in the highlands of Scotland. It landed on the hood of my dark coloured jacket which was drying off in the sun over the saddle of my bike. In the foreground is the brake cable of the bike to give some scale. I measured the area of the hood that the horsefly is sitting on after it flew away, and yes it measured SIX - EIGHT cm!!!! The length of my forefinger!

The Ranger responds: That's the beastie alright. 8cm? That's gotta be a record!
PermalinkPermalink 19/07/09 @ 22:02

 

Comment from: Tabanus
6-8cm? I have heard of fishermans' tales, but never entomologists' tales. If it was that big, you have enormous brake cables. They don't comne much longer than 2.5cm, even in the Highlands.
PermalinkPermalink 27/08/09 @ 19:51

 

Comment from: The Wildlife Gardener Email
This fly species is getting bigger and bigger with each comment posting. I saw one that was 9 cm. Any advance on 9? ;-)
PermalinkPermalink 27/08/09 @ 20:33

 

Comment from: The Virtual Ranger [Admin] Email · http://naturenet.net
I once saw a fly so big it blotted out the sun.

It was sitting on my nose at the time so possibly perspective had something to do with it.
PermalinkPermalink 28/08/09 @ 19:48

 

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The thoughts and writings of The Virtual Ranger, since 1995 the host and mascot of Naturenet, the UK's most popular independent environmental website; along with interjections from his real-life alter ego, Matthew Chatfield, and others. Featuring not only Naturenet and countryside related stuff, but, as on Naturenet, plenty of other material - more or less at random - that takes The Ranger's fancy. But you can be confident that soon enough he'll be rather sarcastic.

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