The Parachute Adams is a classic fly that I've come to depend on.
My last eye check didn't go so well. I've reached a point where if they correct my vision for distance so I can see my fly on the water, then I can't see up close (a fly in the hand). Which means that I have to lift my glasses up to tie flies to my tippet.
The stronger prescription gave me headaches and vertigo and I don't like having to take my glasses on and off. So I fish with a weaker prescription and more visible flies.
That's where the Parachute Adams comes in. When I first started fly fishing I loved to scan the fly bins and pick out flies that "looked good". This meant I had a box full of catskill style flies with bushy hackles and hackle tip wings. The flies were big too, size 10 and 12s because 14s looked really tiny to me when I started. I actually had a pretty hard time finding these big flies on the water despite their gigantic proportions. Fish rarely fell for these guys on the Middle Provo.
I had many fly shops recommend the parachute adams and it's variants but I didn't understand what made this fly work better than say a realistic dry fly (which often don't work well at all on our local waters).
Vincent Marinaro, in his book A Modern Dry Fly Code, breaks down fly design based on function rather than imitation. The Parachute patterns are tied to give a dimpling pattern on the water that would give the impression of legs. And the post would come into the trout's window of view early just like a mayfly's upright wings. It rides with the body in the film like an emerging insect.
All of this may be true because the fly catches fish well and floats a dropper nicely.
Best of all. I CAN SEE IT!