Bats are highly susceptible to rabies and other diseases. As their natural habitat is destroyed and humans encroach they are becoming more of a household pest. If you have a bat infestation their droppings will accumulate where they roost, they will make noise and you might be uncomfortable knowing they are nearby. Their urine appears as milky white streaks on window panes. They tend to make squeaking and scratching sounds around dawn and dusk.