Green-colored feces?

Is it ok for an A. gigas to have green tinted feces? I have always seen only brown. They are not eating any veggies, only vegetation for now. I have a crazy amount of fruit flies and i have not been feeding them anything to prevent more flies. (I think they are there because I am keeping it moist for any A. gigas babies) I do not know who left the poo but none are acting strangely.