Thanks for the replies. I'll tell ya, this gook that was on the hook eyes of these flies was the likes of nothing I've ever encountered.

As suggested, I got all the culprit flies out and laid them in a row, got a couple of sweetie's needles, some matches and I was about to perform surgery, when I was asked what I planned on doing with HER needles. I explained and was told not to even consider fouling up the needles - instead she got a pint bottle of 91% isopropyl alcohol out and suggested I might try that first. So I pour out a little of the alcohol into a bottle cap, dipped the needle and poked it through the hook eye a couple, three times and that did the trick!

Lord knows it's hard taking advice from wimmen (especially when it works) ... and considering they don't even fish!