I don't even know if they would associate ants as a food source. The reason I say this is because were RETF's would come from a lot of the ants are very lethal to small animals, there sting packs enough punch to kill the frog. Like a bullet ant for instance, this ant grows to a inch long which is like half the size of the frog. I know it may be hard to imagine but you never know, you think they would be smart enough to stay away from things that will kill them. If they did eat ants a lot of the ones we have here are very small and very fast, and the bigger species the Carpenter ant I can honestly say you wouldn't want that ant to bite your frog because it would leave a mark and could possibly get infected. I use to keep a huge ant colony of carpenters and it stings abit when they get you, and they will stand up for themselves if need be. I watched about 20 carpenter ants devour a huge junebug within about 20 mins, to the point they were crawling in and out of the bug eating his insides. They may be small but they are very determined little insects, especially when threatened.