Invasive worms containing ‘lethal neurotoxin’ found thriving in several U.S. states: ‘They have the potential to do damage’

Leo Collis
Thu, October 19, 2023 

Gardeners in the mid-Atlantic region may have spotted some unusual worms lurking among their plants, and they could soon be seen in flower beds throughout the East Coast.

Known as the hammerhead worm, the species contains a lethal neurotoxin that is also found in puffer fish. They can also split into multiple pieces that function independently.

Although a human would have to ingest several to be affected by their poison, handling them could lead to skin irritation.

What’s happening? 

The iNaturalist App (via a Washington Post report) said hammerhead worms have been sighted in Arlington, D.C., Virginia, and Maryland in the last 15 years.

According to the Post, it is thought the invasive flatworm might have arrived in the United States following the importing of exotic plants from Asia.

Researchers Yoan Fourcade, Leigh Winsor, and Jean-Lou Justine modeled the potential distribution of five hammerhead worm species amid changes in climate. In data published on the Wiley Online Library, they concluded that the climate on the eastern coast of the United States provided a “higher suitability” for all five types.

Why are hammerhead worms causing problems?

Although humans should suffer minimal problems from coming into contact with them directly, the hammerhead worms prey on invertebrates and can also cause health issues in pets.

Hammerhead worms primarily feast on slugs, worms, and snails. Biologist Amber Stokes, a professor at California State University, Bakersfield, told The Washington Post: “They have the potential to do damage to invertebrate populations, which then risks organisms up the food chain as well.”

When it comes to pets, the Post noted they are carriers of parasitic nematodes, which may result in health complications if ingested by your animal.

While hammerhead worms are already present in small numbers in the United States, the warming climate could lead to an increase in population and distribution.

Fourcade’s, Winsor’s, and Justine’s research showed that “flatworm species were systematically absent from regions exhibiting cold winter temperatures.” It also added that two species of the flatworms “also showed a sudden increase in suitability after [77 degrees Fahrenheit] of maximum temperature of the warmest month.”

The hammerhead worms seem to thrive in hot and wet conditions, and the humidity on the East Coast of the United States provides an ideal climate. Although models of distribution are different depending on predicted climate possibilities, the East Coast was widely forecast as a suitable location for hammerhead worms in the future.

What can I do about hammerhead worms?

If you find a worm in your garden, you must dispose of it safely. They aren’t that easy to destroy, as they can survive when cut and can continue to reproduce.

Naturalist Alonso Abugattas advised the Post on the best process when trying to get rid of the creatures.

“People should wear gloves when dealing with hammerhead worms,” Abugattas said. “The worms should be placed in plastic bags with alcohol, vinegar, or salt and frozen. The big thing is to freeze them before disposal.”