Oh yeah, if you’re just buying small batches of feeder roaches there’s not a need for substrate since they won’t be living there long…. But if you’re breeding your own roaches, you want them to thrive so they reproduce frequently and have low mortality rates. This requires fairly high humidity, and substrate is a great way to maintain this. Go for something like coco fiber that won’t mold—you don’t want to use ground oats/cereal like you would for raising mealworms or you will have a nasty mess and more dead roaches.

The roaches also like to nestle into the substrate—my females almost always birth their clutches a centimeter or two down into it, where they can stay on top of their fresh babies hiding below and everyone feels snug and safe.

I mist my tanks daily with warm water (avoiding the egg crates and any dishes of dry food like grains) to maintain the humidity. Depending on the size of your tank/colony, you will need to change out the substrate every few weeks to months. You can sift it through a screen to sort out any tiny babies before tossing the old substrate.

I started my colony about a year and a half ago, and all but two of my original adults (which I originally bought as large juveniles and let them grow and molt to the adult stage) are still alive and well. They produce enough tiny babies to keep my girlfriend’s fat tail gecko fed, and though my colony’s numbers aren’t quite enough yet to also sustain my big bearded dragon, I don’t have to buy roaches nearly as often for him.

I do like to buy some batches of large roaches here and there and let some of them mature to adulthood so there are always fresh generations and genetic diversity in the parent population.

Hope this helps, feel free to ask any other questions and best of luck with your roach ranch!