We moved into our 1930's semi 6 months ago. Two weeks ago I noticed small woodworm-like holes in one of the floorboards in the middle of the hallway (floorboards are exposed). I hadn't noticed these holes before so was concerned it might be new woodworm. I carefully filled each hole with filler - there were about 10-20 holes scattered over a 2 foot length of the floorboard. Now, a week or two later, I have noticed more holes in the same floorboard, so I guess it must be live woodworm. I have read about Boron treatments that you can apply to the surface, but my question is, should I just paint this over the top of the affected floorboard, or should I also treat adjoining floorboards, or should I lift the floorboard (which would damage it) and treat the underneath too, and even the joists underneath?? Thanks in advance for your help.
Had this problem in my sisters house which was much older than 1930's.
I used something called Tri Hexylene Glycol Biborate commonly sold with the trade name "Brunol". I treated all timbers under the floor and a face mask was essential.
Not sure if you have to be licensed to get this now as it is a powerful pesticide but it did the trick (I can still smell it now after 20 years!).