In truth, bats are incredibly beneficial to the environment and your home if you would just give them a chance. Merlin Tuttle's America's Neighborhood Bats: Understanding and Learning to Live in harmony With Them gives you the honest truth of these amazing creatures and how your understanding of them is flawed.
Contrary to popular belief, common neighborhood bats don't survive on the blood of the innocent, but rather those pesky insects you complain about all the time. If you are worried about them coming and nesting in your attic or home, then the book teaches you how to build a bat house. The house can provide a living space for the bats, so they can eat all the insects you hate and still stay in your neighborhood.
Far too many people call the exterminator as soon as they see a bat, but by treating them with respect and understanding how they live, you can both survive peaceably. The belief of bats as pests is leading to threats to their survival and if things don't change, they may no longer be part of your neighborhood ecosystem. That would lead to a massive insect increase and potentially an increase in insect-borne diseases.