Dangerous Hammerhead Worms Found Here – Again

Don Steinmann of La Grange discovered a hammerhead worm on the porch of his home in the Lynnwood neighborhood last month.

“We had a lot of rain the day before,” Steinmann said. “I walked outside and there he was, sitting on the porch early in the morning.”

This is the second time I’ve heard of someone in Fayette County finding this invasive, toxic garden pest. Back in 2021, a resident in the Round Top area discovered one on their property.

Steinmann said he read about hammerhead worms but had never seen one before. These worms reproduce asexually by “fragmentation” – if you cut it or crush it, each piece can become a new worm.

“I needed to kill this thing, but I knew I couldn’t cut him in half or stomp on it,” Steinmann said. “So I went and got my blow torch and burned him to death.“ Hammerhead worms are part of the genus Bipalium. The ones here in Texas are probably from the species Bipalium kewense. These flatworms with a crescentshaped head are native to Vietnam and Southeast Asia. They probably got to America through the horticultural trade. The one Steinmann killed was about five or six inches long They can reportedly grow longer than a foot.

According to the Texas Invasive Species Institute, hammerhead worms were seen in America as early as 1901. They seem to be more common in states east of here. By the 1980s, they had been noticed in the Beaumont area. Since then, they’ve been found as far west as Uvalde.

They’re especially harmful for gardeners because they prey on earthworms, one of the most beneficial organisms in healthy soil. They secrete toxins through their skin that are noxious to predators. The toxins also help them to digest earthworms.

You can kill them by spraying their bodies with a mix of orange oil and vinegar. Some folks place them in a Ziploc bag with a mix of vinegar and salt, and then dispose of the bag. Or you can burn them to death like Steinmann did. Just be careful not to touch the hammerhead worm, because the toxins can cause skin irritation in humans.

Steinmann speculated that the worm may have come in with some garden soil he purchased.

“We don’t know where that stuff comes from,” he said. “I’ve been watching out for them, but its the only one I’ve seen.”

Now with two reported sightings in the last few years, I think it’s safe to say that hammerhead worms are here and we should all look out for them.