They moved here, to our farm in Sweden. I just finished cutting and splitting a dead and partly rotten tree. The core of that tree was filled with a good approximation of soil which again was filled with earthworms. They were also slithering between the bark and the trunk in droves - this tree being partly rotten the bark was loose on the trunk - as if they were getting ready to evolve into treeworms.

When it rains it is crawling with the things. Living in the forest and having an unpaved lot probably helps here.