It's not a beetle, it's a biting fly. We've had them around Oxford for a few years now, they seem to like to live near streams (though they can turn up anywhere) and once they've colonised you simply cannot wear shorts or short sleeves. If you get bitten enough you can go into toxic shock. DEET seems to keep them at bay and some of us are naturally not very attractive to them (though I still get bitten occasionally I never seem to be the prime target...