The poster reached out to the r/AnimalID subreddit for help in identifying the long slug-like invertebrate on their sliding glass door.
“What is it???” they wrote. “Is it a worm? Is that a spider it’s digesting?”
The responses poured in, and they were unanimous: It was a hammerhead worm. The invasive flatworms are destroying agriculture, horticulture, and natural ecosystems by killing earthworms, snails, and slugs.
All hands on deck are required when one is spotted. Not only do you have to kill it — carefully — but you also have to notify local officials.
The species can grow to 15 inches, secretes chemicals that can irritate human skin, and may carry parasitic nematodes. It can also cause problems in domestic mammals if the worm is ingested.
They are famously difficult to get rid of, as they reproduce via fragmentation.
As one user advised: “Kill it with fire, stomping it does no good as it segments. Also report to your local EPA asap.”
Hammerhead worms are native to Southeast Asia but now live in the United States on the East Coast, in the South, and as far west as California, according to the Texas Invasive Species Institute.
“They have the potential to do damage to invertebrate populations, which then risks organisms up the food chain as well,” biologist Amber Stokes told The Washington Post.
The pests can be killed with salt, vinegar, alcohol, or citrus oil and should be frozen before being disposed of.
“Continuous removal of these invasive flatworms is necessary for the protection of naturalized earthworm populations,” the TISI stated.
The institute advised wearing gloves or using a paper towel or a stick to handle hammerheads. The worms should be sealed in a bag with one of the aforementioned treatments so they can’t crawl away.
Then, wash your hands in warm, soapy water and rinse them with alcohol or a hand disinfectant.
“Something about the idea of a predatory worm is really unnerving,” one commenter said.
Another wrote: “Kill with prejudice.”
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