As Robo mentioned, use #8 (1/8" squares) when you want to restrict the movement of your bees. If you make your own woodenware, use #8 hardware cloth on your screened bottomboards, ventilated inner covers, and to cover the feeding holes cut in a solid inner cover where you're going to use feeding jars or pails. Also, you can use #8 to screen the entrance when you're transporting your colony.