That's a good point, the food could very well spoil while you're gone. But carrot doesn't seem to spoil very quickly to me, if anything it just kind of dries out on the outside and withers up. If it was humid there is a higher risk of mold I would assume. With my lobster roaches they eat the food so fast it kind of doesn't have a chance to mold. I do think they need something for moisture, such as fruit or vegetables. But water crystals would work along with dry food. To answer you're question, yes I think they need some form of food and water while you're gone depending on how long you're away.