My bathroom is full of woolly bears (carpet beetle larvae) where are they coming from?

[Jippers]

Every day I find these woolly things trundling along the grouting of the bathroom. Where the feck are they coming from? It's the only area of the house that I see them in. The whole house has wooden/tiled floors. Do you think they live inside the dusty fins of the radiator? We don't have central heating so the radiators aren't used. I don't see any damage around the house so I've no idea what they're living off.. Any ideas?

No idea where they come in from but they are quite destructive. As their name suggests they feed on your carpets, so that's their food source. No idea why they are loitering around your bathroom but they handedly located for flushing down the loo.

@Jippers
Did you ever get to the bottom of this as we have the same? Three larvae only in our bathroom this week