curious. why so many? is it just because you enjoy it making them or do you lose them frequently enough while fishing that you need a stock pile?
I carry an obnoxious amount of flies. People make fun of me for how many flies I carry. But I have a reason and it tends to be productive.
I try to match the bug and where it is the life cycle. So every mayfly has 4 parts to it's life cycle.
Nymph - lives underwater crawls around and sometimes just drifts with the current...but below the surface lower in the water column.
Emerger - right before the nymph turns into a fly it emerges from the bottom. A small gas bubble forms on the top of the bugs thorax where the wings will pop out. This air bubble helps rise the bug to the surface along with some kicking and wiggling. This phase happens from the bottom all the way to the surface...and the bug will be in the process of metamorphosis.
Dun - a dun is a fully hatched adult that rides the currents for some time as it's newly formed wings dry. Some mayflies do this very quickly some take a while...weather seems to play a role. Cold damp days bugs will ride the currents a little longer before taking off
Spinner or Spent - After they dry their wings they fly up to the trees to mate. Once they mate the females with return to the water the lay their eggs and die. They drop their eggs air born then fall to the water with their wings laid flat out like a cross. This usually happens late in the day at dusk. And since the bugs cannot escape it creates a gentle feeding frenzy with the trout lined up to gently sip the spent mayflies.
To imitate that I might need 5 to 7 patterns just to cover one bugs life cycle. Then each bug could vary in size so I need those 5 to 7 patterns in 2 or 3 different sizes.
And that's just mayflies there are caddis flys and Stoneflies also.
Right now on the West Branch of the Delaware there are 4 major mayfly hatching. The first number is hook size, they go in 2 increments. So 18-20 is two sizes. 16-20 is 3 sizes 16, 18, 20.
Mayflies
#18-20 Olives
#16-20 Blue Quills
#14-16 Hendricksons
#10-12 March Browns
Caddis
#18-20 Chimarra caddis
#14-16 Apple caddis.