OAKTON, Va. (WDVM) – The Ambrose family clears dead hammerhead flatworms from their driveway in Oakton, Virginia every morning. It’s been a ritual for the past two months, starting when they spotted a 14-inch hammerhead flatworm slithering in front of their home.
Their family dog, Peanut, had the first unpleasant encounter with the worm.
“Peanut’s running up to the house off her leash as she always does and here across the driveway is a stretched-out 14-inch worm,” Kevin Ambrose told Nexstar’s WDVM. Ambrose said the worm stuck to Peanut’s legs and wrapped around her body before splitting in half.
He said he later picked up another hammerhead worm. This time, the worm split into four fragments and squirmed off into the grass. That’s one of the alarming features of the species — it can regenerate from fragments, creating even more worms and exacerbating the problem.
Ambrose isn’t the only one dealing with this invasive worm.
What are hammerhead worms?
The flatworms are slightly brown and yellow in color with crescent-shaped heads, growing well beyond a foot long.
George Mason University ecology professor Chris Jones studies invasive species in the region. He said that there are at least eight species of hammerhead worms, which originated in Asia and first appeared in the U.S. in 1901. Hammerhead worm sightings have increased recently, he explained.
“It hangs around at a very low level. There are things that kind of hang out cryptically and then take off for various reasons,” Jones told WDVM.
The worms aren’t seriously harmful to humans, according to Jones, though the toxins on their slimy skin could be irritating. Jones said pets could get very sick if they ingest the worms, which happened to Peanut.
Ambrose said Peanut vomited up a worm and was sick for several hours.
Where are hammerhead worms found?
The worms thrive in areas that are humid and warm. There are at least 15 species in North America, according to Penn State Extension. Only about two or four are native while the majority have been brought to the country from Asia, as Jones noted.
The shovel-headed worm — which appears to be the most common of the invasive flatworms in the U.S. — has been reported in states primarily throughout the South and Southwest. According to a mapping system by the University of Georgia, there have been positive observations of the invasive species in Hawaii, California, Arizona, Texas, Oklahoma, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Tennessee, Kentucky, Florida, Georiga, South Carolina, North Carolina, Virginia, and New Jersey. They’ve also been reported as far north as Pennsylvania and Illinois.
Among the species native to the U.S. is the diporodemus merridithae, found only in a portion of the Great Smokey Mountains National Park.
What should you do if you find a hammerhead worm?
Regardless of the species of hammerhead worm you find, as long as it isn’t native to the area, the environmentally ethical thing to do is to dispose of them, according to Jones. He said they are harmful to earthworms, which are a crucial component of our region’s ecosystem.
He advises pouring salt on the worms, letting them sit for a few minutes, then putting on gloves and placing them in a plastic bag. He said to then throw the bag in the trashcan.
Remember, cutting the worm in half (or quarters) will not kill it since it can regenerate from its fragments.
Citrus oil and vinegar are also effective in killing the flatworms, but the liquids must be applied directly to the worm, according to Lamar County AgriLife Extension Agent Jessica Humphrey. Penn State Extension also recommends placing the worms in alcohol, or into a bag and freezing them.
For now, the Ambrose family says they’ll continue employing the salt tactic. Ambrose isn’t sure if he’ll ever fully eradicate the worms from his yard, but he’ll continue to clear worms when they can.
“We’ll try to reduce the numbers as best we can just by looking out for them,” he said. “There’s patches of salt on the driveway. When worms go across the driveway, they salt themselves and they’re dead.”