First come the mice... then come the snakes that eat the mice.
Better to handle them before the snakes come.
Yes... call a pest expert to find out how bad and WHAT the problem is. (Because quite frankly it could be mice, rats, squirrels, chipmunks, opossums, skunks, birds, or a whole host of insects -bees & wasps being the most common). Unless you want to poke your head up there to find out...
My personal favorite pest deterrent (before you get to the snake phase) is a good Mouser... but I know some people can't have cats. Even our mighty hunters couldn't keep ahead of the problem though when a new development started going up a few blocks over (nothing chases wildlife into houses like a development).