What size openings should be closed to keep bats out of a building?

Bats can fit through surprisingly small openings due to their flexible bodies. The correct size for closing openings to effectively keep bats out of a building is 3/8 inch. This size is crucial because bats can easily squeeze through gaps that are smaller than what might be commonly expected.

By sealing these openings, you can prevent bats from entering, which is important for maintaining hygiene and avoiding potential health risks associated with bat infestations, such as the transmission of diseases like rabies. The other size options exceed what is necessary for exclusion methods specific to bats, as they can readily enter spaces that are 1/2 inch or even larger. This makes 3/8 inch the optimal choice for keeping them out effectively.