Petes_dragon - simple test for woodlice - if you touch the wee critter gently, does it roll up into a ball ? If so, you've got woodlice ! Harmless btw but just a bit offputting indoors. They are a gardener's friend as they live on dead and rotting vegetation, thus speeding up decomposition. They like to live in moist surroundings, so if you want to discourage them coming into your house, ensure it is dry - you could always sprinkle talcum powder around where they are getting in !