Rough greens are tough snakes to keep alive. If you want a challenge, then that's fine. I would keep no more than one in that cage, and you may need to upgrade; they are slender snakes but may reach over a yard in length. Be sure to keep up humidity. The mesh cage will work if you mist frequently. Care is more or less as for a typical chameleon. House crickets are OK, but they are awfully chitiny compared to the snakes' typical diet (tree crickets, spiders, caterpillars). Roach nymphs might be a better staple. Very small frogs or lizards may also be eaten.