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Invasive worm with “cobra-like” head is found in Ohio. Here’s how to find it

By Sundi Rose
Hammerhead worms have long, flat, slimy bodies and cobra-like heads, experts said.
Hammerhead worms have long, flat, slimy bodies and cobra-like heads, experts said. Screengrab from Warren County Extension Office on Facebook

Ohio has another invasive species, but this one is not as scary or destructive as the Asian needle ant.

The Hammerhead worm is a flat-bodied land planarian that has been in the U.S. since the early 1900s and has likely lived in Ohio for decades, according to the USDA National Invasive Species Information Center.

Although they are technically invasive, they’re basically harmless, unless you are an earthworm.

What are they?

Hammerhead worms, or Bipalium species, get their name from the wide, half-moon-shaped head that makes them easy to spot.

Characteristics:

  • Flat-bodied, not round like earthworms
  • Found in moist outdoor areas such as gardens and mulch beds.
  • Feed on other invasive species such as jumping earthworms.
  • Grow several inches long
  • Active year-round
  • Most visible after rain

Are they dangerous?

Hammerhead worms prey on earthworms, however most earthworms in Ohio are themselves introduced species. This has caused a genuine debate among experts about the ecologically murky situation.

While the worms pose no direct threat to humans, you should still take a few precautions.

Precautions:

  • Wash hands thoroughly if you handle them. They produce a mild neurotoxin (tetrodotoxin)
  • Leave them when you find them. They feed on other invasive species and can protect your yard
  • Don’t call any agency if you find one. They aren’t marked as reportable

How to get rid of them (if you must)

Hammerheads don’t colonize homes, don’t swarm, and don’t breed rapidly the way other pest insects do.

They reproduce primarily by fragmentation, so population explosions aren’t really their thing. If you find one and decide you want it gone, method matters.

Effective methods:

  • Don’t chop the body. Each segment can regenerate into a new worm.
  • Submerge in soapy water they cannot escape
  • Crush them thoroughly with no viable segments remaining
  • Apply salt, a vinegar solution, or citrus oil
  • Wear gloves and avoid skin contact with the worm’s secretions

The hammerhead worm doesn’t present any real danger to you or your pets, so eliminating them may not be the move for everyone, unless you farm earthworms or garden professionally.

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