I would have a lid. Just feels safer to me. I was holding a baby roach when I first got them and I sat him or her on the fern I planted in the enclosure it seemed as though it had no idea how to get down. I am hoping with all my heart to NEVER have to buy another cricket after these guys catch on. My partner says if 1 gets out she'll throw the whole thing out I think Oh yeah...I think that would be plenty big enough can you provide heat in a plastic container? They do need heat to breed...80 degrees I think it was, and humidity.