You'll find fine powdery dust around or underneath the holes.
Woodworm damage is considered to be gradual deterioration and part of the wear and tear of a building, so always check whether your home insurance covers this.
Whilst LV= won't cover woodworm damage specifically, you can add emergency cover to your LV= buildings insurance to cover other pests such as bees, wasps, hornets, rats mice and squirrels.
If you keep on top of the maintenance of the timber in your home, you should be able to spot woodworm before it gets too damaging. Catching it early makes it easier and less expensive to treat.
Woodworm damage is considered to be gradual deterioration and part of the wear and tear of a building.