Yes, indeed.
Last weekend I was hiking up Mt Keen, and paused briefly for a sammich.
I noticed a large fly thing on my arm, and tried to blow it off with a puff of wind from my mouth.
The thing did not move.
A firmer brush with my hand, and off it went, and I had sprung a leak!
The little bugger had probed me with it's proboscis, and was extracting my juice!
I hadn't felt a thing.
It would not stop bleeding for a few minutes; I think it injects some anti-coagulant to keep my juice flowing.
Little bugger.