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This little fly was seen in large numbers at Ham Wall reserve in Somerset on Sunday. About the size of an ordinary house fly, it had extraordinary iridescent bright green eyes. The antennae suggest that it's not a normal hoverfly. Does anyone have any ideas?

I believe that is one of the "Horse Flies" ~ Tabanidae ~ It looks like one that settled on my wrist forty years ago in West Sussex when I pulled up in the road in a heavily wooded promising looking area new to me. It 'bit' me and I slapped my other hand over it expecting it to be crushed but, it was not crushed and recovered its shape and carried on its vampire like pursuits on my wrist ......

Bit scarey that so I took it between finger and thumb and really destroyed the fly. In some ways that was a fortuitous incident as I then parked up and walked deeper into the wood for a comfort break. There right in front of my nose at the tip of a sallow leaf was a 1st instar larva of Apatura iris ~ The Purple Emperor. The little larva was fully fed in its 1st instar laid up ready for ecdysis ~ skin change.

That wood saw many visits over the next few years. It was then the finest wood locality for this butterfly known to me ~ and I've known quite a few localities.

The Tabanidae are a fascinating group of flies. It includes the largest species of true fly found in the British Isles. Have a look at this plate from my Fly Book..



Those two "Horse Fly" species on the left are the largest flies we have ~ like a x3 scaled up version of the very common Clegg which no doubt anyone interested in butterflies has had a blood sucking visit from at some stage in their visits to the countryside.

Thanks for the comments. I didn't think it was a horsefly as the antennae looked wrong, but chrysops caecutiens looks a possible match.

eccles wrote:
Thanks for the comments. I didn't think it was a horsefly as the antennae looked wrong, but chrysops caecutiens looks a possible match.

Just don't allow one to settle on you ~ you may be sorry ~ I swatted two in my own little nature reserve two days ago which tried their luck on me. There is a Stud Farm the other side of the lane about three hundred metres away.

Their bite can be more painful than the cleggs and other 'regular' Horse Flies .... in my experience.

I was clearing some unwanted Hawthorn and Wild Rose to allow these other trees, shrubs and plants to thrive. These flies can be very persistant and in the sultry heat of the past few days, slow work down. Here's where they tried to get me... but, I got them :~


..

Ouch, right in the hazelnuts!