This is the first I've heard of this. Her explanations make sense, but I also wonder if there aren't other factors involved. I haven't fished in a long time, but we used to dump the leftover worms in the lake for the fish. Makes me feel a little less guilty.

We have a good friend who is a PhD in forestry (semi-retired professor). When I remember it, I'll ask him if he has heard of this problem.

For years while doing landscaping, I noticed extremely prolific and active worms quite different from our usual earthworm lovingly known as a "nightcrawler".
These were prodigious and voracious consumers of organic matter and multiplied in disturbed wooded areas or mulched beds, producing light and prilled soil. Many fine rooted perennials refuse to establish in soils where these worms are abundant.
I finally determined these were Amynthas worms.

Rx

Here is a link that might be useful: Amynthas worm info

Marty, what does "prill" mean in this use?

Prill refers to particle sizes.
What I meant was that the worms leave the soil as extremely fine, light, tiny, round worm castings.
It lacks "substance" and appears to no longer have density or proper structure.

Rx

The woodlands of the northern Adirondack Park where I live, like many northern forests, have a very thin layer of litter to begin with and are seriously threatened by these invasives. The threat has been reported for a couple of years and people fishing here have been asked to not "free" any leftover worms at the end of the day.

It's still hard to think of earthworms as an invasive species, especially since I've just started gardening again after moving here from Southern New York. I had relatively few worms when I started my new garden which I should see as a positive sign since my little vilage is surrounded by forest. Their population seems to have grown over this first season season as the permanent mulch seems to be a worm magnet.

If they would stay just in my garden then I suppose they wouldn't be a cause of concern, but knowing that they're out there busily building up my garden soil, I feel a little like those who plant invasives because they arrogantly insist that they know how to control the spread.

I'm still not sure how to deal with this quandry. The robins seem to love my garden, and are seen hopping all over the beds, hopefully pulling up earthworms. Perhaps an "Earthworm round-up" is in order. Any worm wranglers care to mount up and help drive worms back down the I-87 Trail?

Wayne in the Adks.

Here is a link that might be useful: University of Minnesota

From what I understand, there are NO earthworms native to North America. Maybe I mis-understood? April

My readings show there are native earthworm species in the US, pretty much all in the south where they were spared by the glaciers halt 15,000 years ago. There are no native earthworms in the northern US. Few areas in the south have only native worms, mostly the arid areas where the European imports don't thrive.

Wayne in the Adks.

This thread on the soil forum was very useful for further info (towards the bottom of the thread):

Here is a link that might be useful: Earthworm thread

Here is another thread with a discussion about non-native earthworms in northern North America and their effect on forests in those regions. My layman's understanding of the whole issue can be simplistically summarized: they're destroying the forests, but they'll probably do your garden more good than harm.

- wd

Here is a link that might be useful: Another earthworm thread