Almost any fish I have ever kept during my summer camping trips up in the Smokies had tons of black ants in there. The guys at the old Trenthams Hardware store always recommended fishing black ants. I just can't see them and end up missing fish. About 8-10 years ago I started fishing them as a dropper about 6" behind a stimulator, parachute adams, or royal wulff. It's been really productive.
The other great terrestrial I love to drop off the back of a fly is a bright green inch worm. I was on Little River and fished this hole for a long time with no luck. On my way up to the trail I found an inchworm. I get up to the top and throw it off into the water and a fish taggs it within 5 seconds of being in the water. The best pattern I've used has been a silicone rubber swimmers cap that was a perfect match. I don't know what I'll do when I run out.