woodworm, old or new? Help!

[Wiggy29]

Dh is sanding floor of our new house and has found that several floorboards (downstairs) were very soft and several were 'like a crunchie' inside! Ekk! Obviously it's woodworm but how do you identify if it's old or new?

We've consulted an expert (Google) and only real suggestion for new is tiny piles of fresh sawdust which there is no evidence of. We've also (best we can) looked at the joists and there doesn't seem to be any holes in there (thank the lord).

Other than paying a company, are there any other ways to identify if it's old/ new?

Dh read they can only survive in damp wood (house was empty/ partially used for couple of years before we bought). As we've had new heating system installed, he thinks we should just buy treatment& get a decent dehumidifier, while I'm scared that if it's recent and we don't get experts in, they may start on house foundations.

Has anybody had any experience or could advise/ recommend anything/ next course of action?

hoover it very clean, then any new dust will be obvious.

If the timber has already been damaged it needs to be replaced anyway, and new timber should be treated, so should old timber nearby.

woodworm likes timber which is warmish and moistish, so is common around bathrooms and leaking plumbing, or in areas inside the heated and insulated envelop of the home. Lofts are often free of worm except around the hatch where warm air leaks up.

As it is under the floor, verify that your airbricks are all clean and there is a good cold airflow that you can feel with your face. Look especially for sources of damp like dripping gutters or underfloor radiator pipes.

I'd want to make sure that it wasn't rot rather than woodworm too. The woodworm patterns in our 160yr old weatherboard house are very distinctive, the rot is just squishy and crumbly

agree that the sign of live woodworm is fresh sawdust and that they are not too difficult to kill - our builder recommended rubbing meths over the area. Our mantlepiece does now look as though it has been sprayed with a miniature machine gun!