A heat pack is about $2 extra in winter time. Order a bunch of mealworms that won't succumb to cooler temps like crickets or silkworms, or order some blue bottle fly larvae from jada bait. They can be stored in the fridge, do not feed them but remove them from the PINE shavings they come in and store in fresh, dry aspen. I rinse mine in warm water after I separate them from the old bedding so the dust isn't still on them. You can get 2 bags of 1000 for $25 shipping included.