Moved into this house recently- noticed pile of frass sitting on top of interior trim around sliding glass door going to outside. This trim is not tight to the wall. Have seen a few dead small winged and non-winged black ants handing around the area. In this same area, the outside trim looks and and weathered and possibly rotting, but not soft to the touch. This frass continues to build after removing it. This is the only place in or around the house where this is occurring. I cannot spend the kind of money needed to hire an exterminator, as they would want to treat entire house and then some, also killing every other beneficial critter in the area! Please can someone just tell me what insect may be causing this? Picture attached. THANK YOU