Round One. Leica/Lumix Macro-Elmarit 45mm

A couple of weeks back, we started noticing a few large ants making their way around the place.   Nobody else in the building is affected.  A little research reveals that these may be carpenter ants, which like moist wood in which they can tunnel.  We have just such a spot next to the slider.  The moisture had discolored the floor board.  During the summer, I bleached the stain with oxalic acid, and re-varnished the board.  The stain came back when the winter started.  Seems to me there's moisture coming in from underneath, and the ants found the spot.  One of the invaders conveniently expired on top of the bait container.  They need to go.  I'm trying this liquid first until the exterminator can get to us next week. Then we need to understand where the moisture is coming from, and fix it.  Nature's all very nice, but not in our house.  Not a happy camper...