I live in the Copper Valley and have a great many bats living behind the shutters and eaves on my house. They completely wipe out the mosquito population around my property and believe me, that is one huge amount of mosquitoes. As for winter, they spend it in the ceiling of my house. Maybe they are asleep but they knock poop down every so often which is kind of annoying but still way easier to deal with than the cursed mosquitoes. I would hate to lose a single one, they never bother anything and don't ever come indoors.