From Below

They had always inhabited the earth, preferring isolated, swampy places that were inhospitable to man. They fed on creatures unwary enough to come within their reach, but they were satisfied with a drop or two of rich, red blood. Until the night that lightning struck with an almost preternatural vengeance. Then something happened: they began to grow and mutate, developing a thirst that could no longer be slaked by mere drops of blood. They needed more, much more. And they began to writhe and move toward the city, a horde of insatiable, unstoppable things that knew no fear and feared no human in their quest for food. giant leeches attack a town. would make a very good "b" movie