If I told you that a female alien had come down from space, was self-propagating and gradually invading the earth, what would you say?  That as it grew and multiplied, it would gradually kill off our grasses, ferns, buttercups, daisies, nettles.  It would kill off the butterflies, ladybirds and the familiar insects which depend on those plants.  It would knock walls, damage paving, cause erosion of riverbanks and flood defence structures, it would destroy archaeological sites and it would attack homes.  Would you say that I was losing the run of myself?

Because right now, that is what is happening!