The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
...although, the thought of fighting off giant mosquitos while doing so is most definitely an unpleasant thought!
I think we may be thinking about this wrong. In such a world, bugs like dragonflies would likely be swooping down and scooping up trout, not the other way around. Maybe we'd be tying up trout imitations to go "fly fishing".
-Shawn