There are crawlers on my ceiling!

After I came back from donating some wool to a womens' project just off Tower Hill, I noticed some specks on my ceiling. Then I realised that they were moving. I had to gather up all my wits and hoover them off the ceiling. Trouble is, they are still coming out, in twos and threes. I am much too scared to investigate behind the fridge, which is where I think they have hatched. Over to you, husband dear...