Primary forage for crappie in most of our local lakes are threadfin shad, bluegill and bass fry, damselfly and dragonfly nymphs, and chironomids. I don't fish chironomid patterns for crappie.
I use olive bird's nest nymphs as imitations for bass and bluegill fry.
For damsel fly nymphs I use just about any damselfly nymph pattern. The must be hundreds to choose from.
For dragon fly nymphs I use olive buggers, tied on standard hooks and on jig hooks.
For threadfin shad imitations I use grey/white Clouser minnows ranging in size from 1.5 to 3 inches long. Also chartreuse/ white. Also Lefty's deceivers in the same sizes and colors. The larger sized flies can be very important when the crappie key in on schools of larger shad in late summer. When the crappie are in a topwater mood I use small white crease flies or Gartside gurglers or generic panfish poppers.