Technical Abstract: This study compared brood production, honey consumption (in winter only), population growth of honey bees Apis mellifera), and population growth of parasitic mites (Varroa destructor) in hives with screen or wood as floor material. Two experiments were conducted in Baton Rouge, Louisiana; one in winter (19 colonies) and one in summer (22 colonies). In both tests, we established uniform colonies of honey bees by subdividing 30 kg of mite-infested bees. Each colony began with about 11,000 bees, no brood, and uniform populations of mites (127 and 480 mites per colony in winter and summer, respectively). Hives had either screen or wood floors. After the first 20 days of the tests, when no adult bees or mites had yet been produced in any of the colonies, the two treatment groups showed no differences in brood production, honey consumption, or survival of adult bees. However, colonies with screen floors had more mites on adult bees. At the ninth week (the end) of the tests, colonies with screen floors had fewer mites, a lower percentage of their mite population residing in brood cells, and more cells of capped brood. These results suggest that colonies with open screen floors may reduce the growth of mite populations by slowing the rate of entry of mites into brood cells.