These frames provide a non-chemical way to reduce the population of Varroa mites in your hive during the brood rearing season. Place the frame near the center of the brood and remove the frame 2 1/2 - 3 weeks later. Varroa mites prefer drone cells, as a result you will be removing a large population of mites. Simply freeze the frame for 48 hours and place it back in the brood, no need to clean or scrape, the bees will instinctively remove all dead pupae and mites.