When I started the Fly Of The Week CD, I had the same dilemma, how to categorize the flies for the index. Here is my sorting

Dry Flies: designed to float on the water surface, usually representing an aquatic insect.

Wet Fly: designed to be worked beneath the water surface, usually representing a drowned Dry Fly.

Emergers: designed to work in the water surface, usually representing an aquatic insect moving to the surface.

Streamers: designed to work beneath the water surface, usually representing a minnow, crayfish, or leech.

Midge: Any fly that is size 18 or smaller.

Salmon/Steelhead: Streamer patterns who's original purpose was to be fished for Salmon or Steelhead (personnally I use them for Bass).

Saltwater: Fly that who's original purpose was to be fished for Saltwater Fish.

Terrestrial: Fly that represents some insect or mammal that is normally found on dry land but can be found washed into a body of water.

Nymph (Larva, Pupa): Fly representing a aquatic insect in its early stages of development, normally fished near the bottom.

~Parnelli

PS: It is not a perfect system, but is works for me.

[This message has been edited by Steven H. McGarthwaite (edited 11 February 2005).]