as long as it resembles something close to what fish might be feeding on. Theres a fly i've been playing around with lately called a palamino. It immitates a midge coming out of the schuck. However, the tradition variety is pretty basic. Just a small chenile strip attached to a hook, palmered with dubbing and then cased with antron. however, I have been using egg yarn, around the tail to top the chenile which shows a lot more of a molting image. Another one Ive played around with this winter is called a lazer larva. I took the standard old lace larva patterns and decided to top the black thread with a strand of small red ultra wire. That little flash of red under the clear lace give both flash and an image of a blood worm molting into a black midge. The more you get into it, you will do this with hundreds of differant patterns. Tying is all about personalization, but just don't grab a handful of scrap materials wrap it around a hook; call it macaroni and expect that to catch fish!