I am a firm believer in native species over introduced species. To the extent that if I could get away with it the brown and rainbow trout would go in the bushes here. But with insects, do you really know that it was a native? Most species leave lots of records behind when they vanish. Trapping reports, museum specimens, photographs... And by "native" I mean that it occurred in that particular part of that particular stream, not just somewhere in the state. And is it just the big, flyfisher-friendly bugs like Pteronarcys that should be reintroduced, or is it ALL the insects, including the obnoxious ones? A lot of questions should be asked before taking a step like a species (re)introduction. And all the questions should be answered.

You shouldn't, in my opinion, just put in the things that make your life better. If you are going to restore a native ecosystem, take out the exotics and put back in what used to be there before we messed it all up. If you are just going to add a bug so you get a hatch to fish... shame on you.