'Crazy Worms' Threaten America's Trees And Maple Syrup

Crazy worms — an invasive species from Asia — pose a threat to forests, scientists say. The worms can thrash around so violently that they can jump out of a person's hand. They also lose their tail — on purpose. Josef Görres/Plant and Soil Science Department University of Vermont hide caption

Earthworms are often seen as a welcome presence in gardens, and even on fishing hooks. But in the Northeast, experts say invasive "crazy worms" from Asia are creating havoc in forests — and they say the unusual worms are a danger to animals and plants, and especially to sugar maple trees.

"The street cred that they have is hiding the invasion," Josef Görres, a soil scientist at the University of Vermont, says of the worms.

"I call earthworm invasions 'socially cryptic,' " Görres tells NPR, "because folks think of earthworms as the good guys — and maybe they are in certain ecosystems. But in the context of the northern [U.S.] forest, they are relative newcomers that have the potential to have huge effects."

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Crazy worms — also known as jumper worms — reproduce rapidly. They also love to tear through the nutritious layer of decomposing leaves and nutrients that blanket the forest floor — a habit that can be very damaging to forests, including maple trees.

So, what makes these worms so crazy?

"They're really active worms, and the craziness comes from that. They can jump out of your hand," Görres says, adding that the creatures' intense wriggling can launch them into the air.

"And they also lose their tails," he adds. "Some of the species will lose their tails just like a salamander. So that is kind of crazy, too, when you see it."

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The worms don't regenerate a new tail — it's more like a single-use get-out-of-jail card.

"It's a one-time defense against a nasty bird that comes around to pick it up," Görres says. "It splits. The live part of the worm actually sort of slithers away, and the tail keeps thrashing about. So it is basically saying, 'Here I am, you pick me up, I'm the worm.' "

"They are very active," Monica Turner, a University of Wisconsin-Madison professor, once told Wisconsin Public Radio. "They almost seem like worms that want to be snakes."

Although some earthworms can be helpful to gardeners, they can also cause problems in forests. And that's especially true for the Asian earthworms that are classified in the Amynthas genus.

The worms "are pretty much foes for everything," Maine State Horticulturist Gary Fish recently told Maine Public Radio.

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The worms possess a slew of characteristics that make them a problem for forest managers and horticulturists. They're voracious eaters — and while most earthworms delve deep into the soil, crazy worms prefer to stay in the springy "duff" layer of decomposing organic material.

"They eat the forest duff much faster than a lot of the other European worms because they stay right in that duff, they don't go deep into the ground," Fish said. "They stay right at that duff level, and just eat it all up really fast."

Plus, they alter the composition of the soil, creating a texture that's often compared to coffee grounds. The modified soil is ruined for many native plants, as it's stripped of vital nutrients and prone to increased erosion.

The worms can even cause challenges for casual gardeners. "Homeowners may see garden plants killed and may have difficulty growing plants," Minnesota's Department of Natural Resources says.

In these images showing two stands of sugar maple trees, the one on the left has not been invaded by Asian crazy worms, and the one on the right has. Josef Görres/Plant and Soil Science Department University of Vermont hide caption