Two things might help while you are resolving the problem damp or whatever Lay a trail of salt alround the rooms perimeter and anywhere else they might be coming in. at least they will die around the edges rather than trailing on your carpet, or if they seem to be coming from one spot try adhesive copper tape you can get it from some garden centres or from dolls house websites (its used for dollshouse lighting systems) it works if you put it round plant pots so would probably work round a door/window frame