ants come onto all my substrate for some reason too, and i just use paper towel or newpaper. Its a pain with the monitor cages, especially the savannah that eats crickets, any little scrap of cricket or meal worm that gets left i get a 100000000000 ant swarm and they tunnel and nest in the decomposed granite/soil and i have to completely replace EVERYTHING as far as the dirst substrate in the tank. Im still trying to find a way to keep the ants out of it