Keep insects out of the coop..... plant basil or mint around the coop, or other plants insects dislike such as marigolds. Line the nesting boxes with these plants also under the bedding. Make the walls inside the coop a "slippery" material such as plexiglass, lineoleum or tile. Insects don't climb slippery surfaces. Cedar is also good but expensive and doesn't wash as well. Also, use sand mixed with diatomateous earth as a floor.