On a rainy grey day, I grabbed an ice cream pail, and my hat as I headed out the front door. I picked up big ‘night crawlers,’ and little ‘angle worms’ and lots of them. I do not know the scientific names of these slimers but that does not matter for what I will share with you. The two dozen worms collected from the road and sidewalk outside my house I put into my garden and covered with dirt and grass clippings.
I have the worst soil in Rochester for gardening, clay. Maybe my yard is all back fill. I have heard that developers harvest the black dirt from a property before they build and use clay and rocky soil for back fill thus creating a market for good soil. In any event, I figured I needed all the help I could get to turn this clay into gardenable soil. Earlier I had tilled in a full pickup load of horse manure but it had not changed the consistency of the soil much.
I own half an acre of land in NW Rochester; there were no trees on the lot when I moved in. Before I went out to buy trees for my yard I got to thinking about those earthworms that are so good for our gardens and lawns.
Fifteen species of nonnative earthworms in Minnesota, and of those fifteen species, seven are invasive. So what, you might think. They're good for our yards, they're good for the robins, and they've been a boon to the moles. What harm could a slimy, wriggling earthworm possibly do? There are no native earthworms to North America, and that should ring alarm bells for those of us who are environmentally minded.
The lowly earthworms devastate our native forests and plants by eating and making that great black dirt that you and I have come to love in our gardens. They turn the layer of leaves and biomass called duff, which all our native woodland plants and trees have evolved to begin life in over the last 10,000 years, into compact black dirt. Compact dirt cannot support the symbiotic relationships that trees and plants have created to survive with the duff layer. Trees suffocate, plants are eaten, fungi simply cannot grow, but allergy causing mold and ragweed grows well under the new conditions that earthworms create.
If you like flowers in the forest, or if you just like to walk through the cool shade of the trees on a hot summer day then something ought to be done about the earthworm problem.
A recently discovered animal may be uniquely suited to rescuing us from
the pending disaster moving across Minnesota at the rate that fishermen
and fisher women transport earthworms across the state into our beautiful
forests. Long and white, coated in slime, it carries with it a
mass of teeth designed to suck down its only food, the earthworm.
New to science upon being discovered in 2006 in a garden in Wales, this creature evolved in a deep dark cave in a dangerous part of the world. There it developed the ability to slide down the holes earthworms dig and suck them up into its belly like a child eating spaghetti. This blind, pale slimy creature never sees the light of day; finding it’s pray by chemical signatures. It is the terror of earthworms everywhere: the Ghost Slug.
The Ghost Slug should be studied as a potential biological control to the earthworm problem here in Minnesota. What is happening to the biodiversity of our forests will cause real harm to us as Minnesotans. I do not know about you, but I am proud to be Minnesotan, and want to see our forestry industry, and our naturally beautiful forests and woodland plants preserved for the well being of my generation, as well as those to come. Though the worms are here to stay, we can control them so that they cause less harm to our forests and give our trees and plants a chance to adapt to the changed world we have created for them. I believe it is the least we can do.
Want to take action to protect the forests of Minnesota from the earthworm invasion? You can contact the Minnesota Worm Watch and the DNR and tell them about the Ghost Slug. Ask them to fund a research project to determine if it is a viable biological control for earthworms. Worms in my garden and compost are fine; in our forests, non-native earthworms are a slimy nightmare.
An avid birder, Andrew Pruett lives and works in Rochester, Minnesota, and joins the team at Bluestem Prairie as an environmental writer.
Editor's note: We urge caution and thorough study before any new species is introduced into Minnesota's ecosystems. While ring-necked pheasants have been welcome additions to our fauna, zebra mussels, flying carp, starlings and other non-native species are creating havoc. We don't know what the Ghost Slug will do to our native worm species.
Photo: The Ghost Slug Project, National Museum Wales.