Im no pro, but i can give a suggestion. If it were me, Id try to get a shifter like u would find in a kitchen. Big enough for a pinhead, but small enough for an adult. Shake a mixed population over it, cover and shake vigorously. I think the pinheads would fall thru and voila! Also, u could try a box with small holes and put food in it. Small cricks will go in only. As for food? I raise them on fish flake and veggies. I have never bred... to much trouble and they STINK!!!