On a summer night, you'll see it being full of insects after 1 hour of operation.
Is also why I started putting up bird feeders and nesting areas -- they control insects including the mosquitoes, and after seeing just how many were out there...
Bats can contort to fit almost any hole in the house. They are effectively tiny mice.
And just like nice, they make noises with their claws when they get into the walls (they will ryn when not airborne and quite fast too)
And their poop will bring hordes of cockroaches....
We used to have them in a lab I worked in and occasionally a larger insect (e.g. wasp) would get caught between two rows of the grid and you'd hear it spark / them cook...