I've caught trout on dubbed/hackle ants that inadvertently pulled the plug; never have fished a true sunken ant, although I hear they're dynamite. Fished with my wife's cousin, Mike, a few years ago on a little stream in NW Montana that saw a few locals and not much else; did pretty well on a bunch of 7-10" cutts using an Elk Hair Caddis while Mike used a spinning rod and Mepps. I caught up to him later in the day while he was fishing a very deep pool and saw him haul in back-to-back 18" westslopes using what turned out to be (formerly) live grasshoppers and 5 BB split shot. Went back there a couple times and tried sunken hopper and cricket patterns (imagine a Letort Hopper with 20 turns of non-toxic; an absolute joy to cast on a 4wt) but couldn't get them down deep enough fast enough to where the fishies lived. I guess a Green Weenie could be considered a sunken caterpillar/inch worm; been a while since I used one but they sure did work.
Regards,
Scott