Whatcha do is, get yerself of of da bugs, and then you look at it. Then you get out yer tying stuff, and then you poke through yer tying stuff until you find the stuff that is the same color as da bug, and then you put a bunch of it together on a hook so's it looks like da bug. Then you go try dis fly and see if da fish like it. Repeat dis process until da fish like it.

DG, reinventer of the wheel.

Seriously, this is how I tie flies to match hatches. I do have a western march brown pattern here that sorta works (hee hee) if you want to start with that. No idea what an eastern looks like.

PS. Found one on my front walk last night after work. Lost little thing.