The “jumping worms” kill rivals and leave the ground sterile, and they also accumulate toxic heavy metals in their bodies that can be deadly to any bird that eats them
An invasive species of worm known as the “earth shark” is raising serious concerns in parts of the United States after being introduced as food for zoo animals.
The species Pheretima, also known as “jumping worms” or “crazy worms,” has already wreaked havoc in the American Midwest and is now spreading to the Northeast.
“Their activity has brought down stone walls in New England,” scientist Gale Ridge wrote in a recent warning.
“Many native trees and plants (including garden plants) cannot germinate or develop in this altered soil, while invasive species thrive.”
“Jumpworms” don’t actually jump, but are excellent climbers and have been found in fairly tall buildings.
“These are earthworms on steroids,” says Ridge, who works for the entomology department at the Connecticut Agricultural Experiment Station in New Haven.
Jumping worms are “remarkably fast, highly active worms with a strong rigid muscular body that can whip violently when disturbed,” writes Ridge.
They were first introduced to the United States in 1948 as food for Australian platypuses at the Bronx Zoo in New York.
Recent severe storms have spread them over a wide area, where they are rapidly crowding out native species and rendering the soil barren.
Because they tend to accumulate high concentrations of heavy metals in their bodies, they can be highly toxic to native birds.
They can also increase greenhouse gas emissions from the soil by up to 50% – double that of European earthworms.
The worms are most active in September and October, but there are concerns that rising global temperatures will allow the fidgety pests to reproduce twice as often, resulting in two generations per year.
There are currently no proven control methods or pesticides approved for use against jumping worms.
Authorities recommend that any gardeners who find the features – which have a distinctive “collar” behind the head – drown them in soapy water or bag them up and leave them to die in the hot sun.
Even if you think they’re dead, the Connecticut warning stresses, don’t just toss the bodies back into flower beds: “Some could be stunned, recover, and continue to reproduce.”