Whats the story on North American earthworms?
Dear Straight Dope: What’s the true history of North American earthworms? Through various haphazard library and online research, I have come across three theories. Please confirm or debunk the following: 1) North America lost all earthworms in the last few ice ages and the ones we see today are immigrants from the human colonists from Europe (hmm . . . which also had many ice ages). 2) North America has many species of its own earthworms, but they are being almost totally ousted by European imports. 3) The worms we see in our backyards are and always have been native to North America. Please sort out this all out. — A. Oberheim, Pennsylvania I’ll vote for (4), none of the above. First off, all of North America was not scraped down to bare rock during the ice ages, and that’s about what it would take to wipe out all the earthworms. It might be fair to say that much of Canada was stripped of its native earthworms last time around, but relatively little of the U.S., and none of Mexico, wa
