IMO, if you don't treat all areas, you are spinning your wheels. All areas except Koy ponds and swimming pools are treated when I apply. Winter gets cold enough here that they seek out heat sources such as landscape lighting and things that hold radiant heat such as stones that are used in landscaping. I automatically add 2000 sq. ft to the lawn area when pricing Fire Ant apps to the customer over the phone so all areas and material costs are covered.
"The Poor Fish" circa 1930's: The Poor Fish wouldn't have been caught if he'd known enough to keep his fool mouth shut.