It's the worms' turn

Jill Severn

A recent episode of NPR’s Bird Note reported a surprising fact: The worms robins pluck out of our grass are not a native species.

The native earthworms of the northern U. S. were wiped out by the glaciers of the last ice age, which ended about 10,000 years ago.

Today’s worms are the descendants of immigrant worms early European settlers brought with them, hidden in the plants they brought with them, or in the ballast in their ships.  

 Incredulous, I did further research to confirm or deny this news. Could immigrant worms really have migrated across the whole breadth of the northern U. S.? 

 They could and did. They had some help from settlers traveling west. But worms, it seems, are prolific breeders. They are hermaphrodites; each worm produces both sperm and eggs.

While a single worm can reproduce by itself, their usual practice involves two worms mating. Their copulation produces offspring whose parent is mother to some of its hatchlings and father to others.

Thus, they are a living rebuttal to President Trump’s executive order declaring that in America, there are only two genders. You might think of worms as the underground resistance to that executive order. 

 Worms are, of course, a gardener’s friend. They digest compost, manure, and rotting vegetation and make all their nutrients immediately available to plants. They aerate the soil, making it more receptive to both roots and water. A soil rich in worms is a rich soil. 

 A recent experience made me grateful for their work. I had piled up a fragrant load of horse manure and covered it with a tarp, and soon it was teeming with red wiggler worms. I had never seen so many worms. They quickly digested the manure.

In just a few weeks, the pile became black, lightweight, and ready to nourish the soil — gardener’s gold. And then the worms in the remaining pile almost completely disappeared.

Did they go off in search of a fresher pile? I’ll probably never know. I hope they left eggs behind, and their offspring will show up in the garden beds I spread their lovely poop in. (Scientists call worm poop "cast.") 

 Since then, I’ve learned that the fine black hummus the worms produced is called vermicompost, and it’s an expensive commodity. Its value is far greater than ordinary compost because it is such a concentrated source of immediately available plant nutrients — a superfood, easy to digest by plants ranging from houseplants to tomatoes to trees. 

 It was pure luck that my manure pile had an optimum combination of moisture, temperature, and tarp for the speedy production of vermicompost. And I’m guessing there were already a few worms or worm eggs in the manure when I piled it up.  

 Fast work and fast reproduction are what makes red wiggler worms so popular. People buy red wigglers online for worm composting bins. You can get 250 for $29.95.  

 There are other species of garden worms too. Puzzled by what they are and frustrated by online sources that are unclear and contradictory, I asked around to find a local worm expert, and was referred to Gary Kline, the founder of Black Lake Organics, which is now renamed Blossom Organics Garden Store. 

 Kline is a composting guru, with strong opinions about what to put in a compost heap and how to do it. He appreciates worms because, he writes “Their innards are essentially a mini-composting chamber.” 

 But as to the other species of worms in our soil he says, “Let’s just call them garden worms.”  

 There doesn’t seem to be enough curiosity or concern about worms for the state Department of Agriculture or the local Conservation District to employ worm experts or researchers. 

 But there is one worm species of growing concern. It’s an invasive one from Asia that does the opposite of our usual garden worms: it robs soil of nutrients. It’s still rare in Washington, but it’s important to keep it that way. It is now migrating north through the Willamette Valley.

According to an essay by the Yakima Master Gardeners published by Washington State University, these worms “are easily identified by their snake-like slithering, violent thrashing, and jumping up to an inch into the air above the soil.” (I apologize if that gives you bad dreams.)  

 I was sad to learn of evil-doer worms. But the Earthworm Society of Britain’s website notes that there’s still a lot we don’t know about earthworms because, “Unfortunately in the past they haven’t commanded anywhere close to the amounts of money for research that, for instance, mammals have, but with their importance being recognised more and more this will hopefully change. Societies like ourselves will hopefully also start to make a difference!” 

 I imagine members of the British Earthworm Society will attend an international worm conference this June in California. 

 So bravo to the worm-curious British and their excellent website. And may all our beneficial earthworms live long and prosper. 

Jill Severn writes from her home in Olympia, where she grows vegetables, flowers, and a small flock of chickens. She loves conversation among gardeners. Start one by emailing her at  jill@theJOLTnews.com