A single phrase from Mark Cocker's Guardian Country Diary item last week just leapt out the screen at me:
Heather flies were everywhere.
Heather flies? What are heather flies. Surely these must be the insects I saw swarming above the heather near Mount Skip last month.
A quick bit of Googling indicated that they probably were indeed heather flies [Bibio pomonae]. And those things dangling behind them are most definitely legs!
It shouldn't be this difficult to identify insects.