All black body and head, with transparent delicate wings.
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Pardon my ignorance, but what species is a Bibio - fly?
I think it is St. Mark's Fly, because it is wholly black and appears to have black hairs on the body. The dark edge to the wings is then typical of male marci. The hairiness is no different to other Bibio, really, and does not differentiate between them.
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The timing is also a good clue as St Mark's Day is April 25th.
...although several of the other species are also very common at the moment, too.
several resembling these out flying today at the reservoirs, with legs dangling down, again does that narrow down the species?
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The dangling legs are a feature of various different Bibio species when they swarm. Size and colour is your best guide, as B. marci, the St. Mark's Fly, is quite a large, all black species, with wings around 10-12mm, whereas other species around at the moment are mostly smaller or have orangey leg sections. Near to me, St. Mark's Fly is only just beginning to appear, while the other smaller species are very common and have been for a month or so. In a week or so, it wil be marci all over the place.
these were easily that size, and all black. Not quite 'swarming' perhaps but several milling about along on the tracks between reservoirs
There have been hundreds around the chine and the small common and have been about for a week now, both flying and settled on plants.
Lat/Lng: 50.7203, -1.84605
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