Hammerhead worms on the rise in Louisiana

(05/06/22) BATON ROUGE, La. — An invasive, wriggling creature with a head that resembles a hammer has been showing up lately in some south Louisiana lawns.

They’re called hammerhead worms. LSU AgCenter entomologist Nathan Lord said it is believed they were imported from Southeast Asia in the soil of ornamental plants.

“Although they are likely to occur across the state, it may be more common to see them in southern Louisiana, as the high temperature and humidity is most similar to their native ranges,” he said.

These worms are called planarians, Lord said, and they are predators of earthworms.

“In theory, a very large population of them could eat enough earthworms to disrupt a garden or the natural soil turnover,” he said. “But this is unlikely.”

Hammerhead worms shouldn’t be touched with bare hands — and they definitely should not be eaten, Lord said.

“They actually produce a pretty nasty neurotoxin for paralyzing their earth worm prey,” he said. “So there is certainly the potential for people and pets to be harmed if the worm is eaten or touched.”

Neurotoxins are substances that can cause damage to nerves or nerve tissue.

“Worms are also really good about having worms of their own, so the risk of parasite transmission from hammerhead worm to human is possible as well,” he said.

Hammerhead worms are not the easiest to kill.

“Planarians are well known for their regenerative ability,” he said. “They have specialized cells that allow them — and a number of other organisms — to regenerate parts of their body or sometimes even entire new bodies from a small piece of the original worm.”

But this does not make the organisms invincible. The regeneration process usually takes many weeks, and it is likely the worms will die due to other factors in that timeframe, Lord said.

These soft-bodied worms need to stay moist to function, so getting them in the bright sun for a while or dousing them with a healthy amount of salt should do the trick, Lord said.

Hammerhead worms have been spotted in several states, with little to no detection in the Great Plains.

Hammerhead worm.

A hammerhead worm discovered by a Denham Springs homeowner. Photo provided.

5/6/2022 8:32:41 PM
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