We have a gentleman who has a large old barn. The bats are making a big mess and he would like to get rid of them. It is not possible to seal all of the holes. I have already suggested that they are beneficial. Any answers?

As you suggested, bats are very beneficial. They eat mosquitoes (potential carriers of West Nile Virus), corn borers, and other insects that can have negative impacts on people. If he is determined to get rid of the bats, he will have to hire a licensed Nuisance Wildlife Control Operator who has experience with bat removal. He can find a list of Bat Exclusion Contractors at: http://web.extension.illinois.edu/wildlife/professionals.cfm He should be aware that given the lack of adequate natural habitat for bats in IL, a new colony of bats is very likely to find the barn.