In many parts of northern North America, there have been no earthworms since before the last ice age. Now, with help from humans, invasive earthworms are colonizing new areas. And in areas of a forest with more invasive earthworms, there are fewer insects, …In many parts of northern North America, there have been no earthworms since before the last ice age. Now, with help from humans, invasive earthworms are colonizing new areas. And in areas of a forest with more invasive earthworms, there are fewer insects, …