The latest invasive creature to make itself known in Northern Virginia and the rest of the area seems gross — until you get to know it. Then it’s disgusting.
The invasive hammerhead worm that recently made news after being found in Oakton has been drawing attention because of its ability to regenerate and its gross method of eating, but entomologist Mike Raupp, of the University of Maryland, says it’s been slithering around Virginia for years.
The worm was first described in England’s Kew Gardens in the late 1800s, says Raupp, a professor emeritus and author of the Bug of the Week blog.
The worms were first sighted in the U.S. in 1901, and it’s “still a mystery” when they got to Northern Virginia, he says.
“But there are hundreds of records of this thing in the DMV in the last 15 years,” Raupp adds. “The best bet is they moved in with greenhouse plants.”
No natural predators seem to have arrived with them, and Raupp summarizes the hammerhead worm reaction as “Oh baby — I love America!”
Breaking Up is Rather Easy to Do
You can check out the website iNaturalist to see reports of the worm, and other creatures, over the years. For the invasive hammerhead worm, look up its Latin name — bipalian, which means “two shovels.” (That’s exactly what its head looks like — the spades of two shovels stuck together.)
They devour their prey by wrapping around them, immobilizing them with a toxin, and sticking part of their digestive tract into the prey, slurping up their insides. And if you squish them or bash them with a shovel, they’ll just break in half, and now you have two worms.
Once an invasive species moves into a new area, its range expands, Raupp explains. The population can vary from year to year thanks to a number of factors — weather, predators, host plants, and more — but “almost always,” he says, the population is expanding in the big picture. It’s too early to tell whether the population is up this year.
It’s hard to predict its effect on the ecology, Raupp says. “We don’t know” what the danger is. “We brought an invasive species.” The hammerhead worm preys on other invertebrates, such as earthworms (which are also non-native), slugs, and snails.
Earthworms are good for the soil, of course, and Raupp says he’s seen a report that the worms wiped out entire earthworm populations in sections of England and Ireland. “That’s not good news,” he says, adding that the report isn’t confirmed yet.
Here to Stay
There’s no known chemical control for the worms, and while other organisms such as nematodes can do them in, Raupp says he’s “a little bit pessimistic that we can eradicate them. I think they’re here to stay.”
He hastens to add that they’ve been here for a long time, and we don’t yet have a grasp on the long-term effects.
“I’ve been working with invasive species for 40 years,” Raupp says. “Much like global climate change, or urbanism, or whatever, species are going to be redistributed around the world.”
Most of the time, the effects aren’t catastrophic.
“What this means for our ecology, we don’t really know,” Raupp says. “This is not one to push the panic button on, I don’t believe.”
Fighting Back
So, what can you do about them?
One thing’s for sure, Raupp says: Don’t grab them or try to pull them out of the soil. They’ll just break in half and regenerate, because they’re — well, simpler life forms. “I don’t want to to call them lower life forms,” Raupp cautions. “I don’t want to offend the flatworms of the universe.”
The hammerhead worms excrete the same kind of toxin found in puffer fish — the kind of fish that’ll kill you if they’re not cooked right — and while you’re unlikely to chow down on them (right?), a dog could get sick from them, and humans can get a skin rash from them.
“You don’t want to handle these with your bare hands,” Raupp says, but sprinkling salt on them or spraying them with vinegar ought to do the trick. “They’ll ooze out vast amounts of mucus and slime, and then they’re easier to handle.” (Fantastic.)
After that glorious process is over, don’t get cocky. You’ll want to gather them up in a plastic bag and put them in the trash, even after they seem dead: “You want to make sure they’re DEAD dead,” Raupp says. “They might just be immobilized.”
He adds (as if you needed to be told) that you’ll want to handle them with rubber or latex gloves even after you’ve killed them. He doesn’t know how long the toxin takes to break down, but “I wouldn’t mess with it.”
Featured image courtesy Mike Raupp
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