Snap traps, also known as rat traps, as they are more commonly used for catching rats, also work for squirrels, which are similar in size. A squirrel investigating the bait on this trap can trigger the rat trap, killing the squirrel. But they may not work for all types of squirrels, says Dickens. Gray squirrels, he notes, are “too large for the trap to function properly,” whereas “red squirrels and flying squirrels are smaller species and can easily be trapped by rat traps.”