- There’s an invasive species of worm making itself known in Texas once again—the hammerhead flatworm.
- These worms are toxic, hard to kill, and dangerous to native critters like earthworms, but likely pose little danger to humans or larger animals.
- Experts encourage people to kill these worms on site, and to avoid touching them directly, as the toxins they produce can irritate skin.
They might not be as ferocious as the sandworms from Dune, but hammerhead worms are nothing to sneeze at themselves. They’re toxic. They can carry parasites. They can grow to over a foot long. If they're cut in half, both halves regenerate. And they’re invading Texas.
Well, strictly speaking, they already invaded Texas. News of the presence and continual re-emergence of this invasive species has been circling for some time, but the recent heavy rains of Hurricane Beryl have brought upsettingly large numbers of these worms—which thrive in wet, tropical climates—to the surface.
Hammerhead worms are a part of the phylum Platyhelminthes, which includes all flatworms. This genealogical membership gives them the ability to become two different, genetically identical flatworms if they are cut in half—a process that can actually be initiated by the flatworm as a form of asexual reproduction. The worm will break a part of itself off that will then grow into a genetic clone of the parent worm.
That’s very strange to think about, but it’s not the reason experts are warning people about hammerhead worms emerging in their backyards. The caution is twofold: the worms are invasive, and they are toxic.
Now, they are not the kind of toxic that will kill a human. Some species of hammerhead worms produce a type of neurotoxin called tetrofotoxin to hunt creatures such as earthworms. They will paralyze a worm with the neurotoxin (found in the mucus secreted by their skin) and clamp on, digesting whatever unlucky part happened to be most accessible.
Sounds scary, but the hammerhead worms cannot bite or inject that tetrofotoxin into humans or animals. According to entomologist Theresa Dellinger, who spoke in a statement from Virginia Tech, “The likelihood of hammerhead worms harming people or animals is low and would require getting the mucus in the mouth or eyes.” Even then, however, the most likely symptom of contact with the toxin is irritation—though, experts recommend reaching out to an appropriate medical or veterinary professional with even mild symptoms like this (and definitely don’t eat, or allow any children or pets to eat, any worms).
So, they’re not super dangerous to people or animals. But they are still invasive, and the kind of invasive that can really damage an ecosystem. According to the conservation group Buglife, these worms—which likely came to the U.S. from Asia along trade routes—reproduce very quickly, they are difficult or impossible to eradicate once established in an area, and they post a threat to native and beneficial crawly critters like the aforementioned earthworms through direct predation. And on top of all that, they can carry parasites, which can be bad news for a variety of organisms.
As such, much like with the invasion of the spotted lanternfly that has been blasted across news sites for the last several years, the recommendation for dealing with a hammerhead worm is to kill on sight. There are a few solid ways to do so, most of which include placing the worm in a container (while wearing gloves, of course) and either filling that container with a substance or placing it in an inhospitable environment. Salt, vinegar, hand sanitizer, soapy water, and citrus oil should all work, as should freezing the worm overnight or placing it in direct sunlight for several hours.
Considering how entrenched these worms have become (there are established populations in Texas, Alabama, California, Florida, Georgia, Louisiana, Mississippi, North Carolina, and South Carolina, according to the Austin American-Statesman), they’ll likely continue to be an upsetting-looking nuisance for the foreseeable future. So, feel free to get to stomping. The fewer worms wriggling up from the ground, the better.
Jackie is a writer and editor from Pennsylvania. She's especially fond of writing about space and physics, and loves sharing the weird wonders of the universe with anyone who wants to listen. She is supervised in her home office by her two cats.
