Re: tying hardy flies.
I've used both Sally Hanson and super-glue on the heads of flies and found both work well. Some flies have a tail, either of feather barbs or something similar. Most commercial tyers don't put any treatment on the fly until they get to the head. As the tail loosens up, it will usually cause the fly to "unravel" so to speak. For that reason, I sometimes put a drop of glue or SH at that point to prevent loosening. Especially with popping bugs, where you put the tail and hackle behind the foam or cork body, it is important to put some cement. I've gone back on purchased poppers and put a little at the tie in point. Be careful you don't goop up the feathers or hair. You can do the same on flies, just be careful. And some of the super-glues will "wick" quite a ways into the hair or feathers, so go sparingly. Good luck.