Ditto!! Mine eat the little black ants that we find around here, but there are types of ant that I would keep them away from. Most of those don't live in the USA. My rule is that if it is harmful to people, then they are harmful to chickens. Here is a short four part NOVA story on some:
Same with my flock of eight girls! I even found a bunch of ants on a rock, and brought the rock in, thinking they'd love it! I don't know if they can't see them (these are the really small black ants; I wouldn't give my girls the stinging red ones, just in case) but they simply ignore them. They also won't eat some millipedes, even though I know they can see them, and while they used to eat the hard-shelled rollypolly bugs (pillbugs) they no longer will. I don't know if they got upset stomachs, or what, but they absolutely refuse to peck at them. They still love earwigs, soft pillbugs (potato bugs is what I call those), most beetles (there's a couple they don't like), worms, most millipedes, centipedes, craneflies, etc. I actually brought some shale rocks into their run and set them in a formation in the center of the run. About once a week, I roll each rock over so they can scratch under it and eat the earwigs that live under them. Any time we find ants, though, they ignore them. It's odd.
Edit: Oh, and crickets! I can actually hold those out to them... I did that just the other day, found one in an old soda can and held it out to one of my girls, and she did this happy, surprised, squeeky cackle and snapped it right out of my fingers.