Unsure fly?

Unsure fly?

Observation - Unsure fly?. Description: Have not found an image of this yet, seemed to have clear wings and hind legs have a thickening at top, black mark at joint, quite small at around 5-7mm, on fresh Hogweed i think. Need help with ID please, Thank you.

Have not found an image of this yet, seemed to have clear wings and hind legs have a thickening at top, black mark at joint, quite small at around 5-7mm, on fresh Hogweed i think. Need help with ID please, Thank you.