I found some (apparently now vacant) "mud tunnels" in a wall void behind some drywall, in an area where water damage had occurred "over a winter." (This is in Utah FWIW--apparently we have both termites and carpenter ants present). Any guesses? termites? Carpenter ants? and more . Thanks!
Confirmed by the "spider control guy" as termite damage (sometimes they do free inspections, you can ask). Guess those little brown streaks (that are hard to peel entirely off) are normal termite "mud tunnels" (I've heard carpenter ant tunnels can at times make tunnels as well, but I guess it's pretty rare and perhaps only in 'more exposed' areas'? Inside the walls you'll just "see tunnels through the wood" not mud tunnels on the outside of the wood as I did. Carpenter ants apparently leave behind a lot of sawdust, as well. So sawdust with tunnels through wood (smooth tunnels, it seems), means carpenter ant. Tunnels through wood accompanied by other "mud tunnels", termites. I guess.
If you get reports of "flying ants" in the spring, that can also be termite. Or possibly carpenter ants as well, they both having fly off swarms. Not to mention if they're "black" ants (inside the wood), that's probably carpenter ants, vs. little white buggers, that's termites. Though the flying swarmers seem to be dark for both. Take one in to your local pest control or farm extension service and they can ID them for you.