Once a bat moves in, they attract other bats, which damages the insulation with guano pile up. There's also a health risk for the household with having a lot of bat droppings inside the wall.

N.C. Wildlife Resources Commission (NCWRC) recommends that homeowners check now for bats that may be getting into their home ...

Maybe that’s OK. Depends on your tolerance to having some guano (bat droppings) pile up around your house, potential exposure of children and pets.” “I wouldn’t say bats are ‘attracted ...

Bat "evictions" are prohibited between May 1 and July 31, so North Carolina wildlife officials are urging homeowners to check their attics and chimneys now.