The bin: smooth, dark, and stacked with egg crate
Start with a solid plastic storage bin with smooth interior walls — dubia cannot climb smooth surfaces, so no slippery barrier is needed, though a screened panel cut into the lid gives the airflow that keeps the colony healthy. Inside, stand egg crate flats upright in a row, like files in a drawer. The crates give hundreds of roaches hiding surface in a small footprint, and upright stacking lets droppings fall to the floor instead of fouling the harbourage. Keep the bin somewhere dark, quiet, and warm; a cupboard or closet corner outperforms a bright shelf, because dubia breed best when they feel hidden and are rarely disturbed.
Leave the floor bare or add only a light layer of substrate. A bare floor makes cleaning and nymph-counting far easier, and the roaches do not need bedding to breed.
Heat is the whole engine
Dubia are tropical, and breeding speed is set almost entirely by temperature. Aim for warmth in the high 80s to mid 90s °F inside the bin, supplied by a heat mat fixed to one side or under one end and always run through a thermostat so it cannot overheat. At room temperature a colony survives but barely reproduces; warmed properly, females produce new batches of live-born nymphs on a steady rhythm. A simple thermometer inside the bin tells you the truth — guessing from the room temperature does not, because the mat warms one zone and the roaches cluster where it suits them.
Stocking ratios and food
Adult males are the winged ones; females are broader and wingless. A ratio around one male to three or four females keeps every female producing without surplus males competing and stressing the colony. Feed a varied dry staple — plain oats or a simple roach chow — alongside fresh offerings: leafy greens, carrot, squash, and sweet fruit. Keepers widely note that oranges in particular seem to encourage breeding. Fresh food goes in a shallow dish so it can be lifted out before it molds; mold and the grain mites that follow damp food are the two classic colony crashes. Provide moisture through the fresh food or water crystals rather than an open dish, in which nymphs drown.
The patience clause, and harvesting honestly
A new colony is a savings account, not a current account. Expect several months of feeding and warming before nymphs appear in real numbers, because the founding females need to mature and produce their first litters. Harvest lightly at first — take surplus adult males and a few large nymphs — and only draw hard once you are seeing every size from tiny newborn to adult at once. Sorting is easiest with stacked sieves or drilled buckets that let small nymphs fall through while adults stay put. Note that dubia are restricted in some regions as an invasive risk, so confirm they are legal to keep where you live before you start. KinsLe's Care Teams lets you put the colony's fresh-food days and monthly clean-out on a duty list, which keeps production steady when life gets busy.