Hammerhead Worm

Hammerhead worms belong to the genus Bipalium and are terrestrial flatworms characterized by their unique hammerhead-shaped heads and have been found in Ontario.

Appearance

• Hammerhead worms are long and flat, resembling a ribbon or tape.
• They typically range from a few inches to over a foot in length
• Their most distinctive feature is their broad, hammer-shaped head, which contains sensory organs and a mouth.

Habitat and Spread

• Hammerhead worms thrive in moist environments such as gardens, forests, and agricultural fields.
• They are most commonly found in soil, leaf litter, and under logs or rocks.
• These worms are highly adaptable and can spread easily through human activities such as transportation of soil, plants, or gardening equipment.

Impacts

• Hammerhead worms are predators of various invertebrates, including earthworms, snails, and insects.
• Their predatory behavior can disrupt ecosystems by reducing populations of native species and altering soil composition.
• In areas where they have become established, hammerhead worms may contribute to declines in earthworm populations, affecting soil health and nutrient cycling.
• The hammerhead worm has a neurotoxin called tetrodotoxin which can be lethal to other organisms such as earthworms.
• Due to the small amounts of tetrodotoxin found in the worm they are not lethal to humans and larger animals. However it can cause skin irritation (Itchy, swollen, tingly) and if ingested it can cause upset stomach in both animals and humans.

Control and Management

• If you encounter a hammerhead worm, picking them with a shovel or with covered hands and disposing them in soapy water or vinegar and salt in a sealed container or Ziploc bag. Once killed you can dispose of them in the container or Ziploc bag.
• DO NOT CUT THE WORM INTO PIECES, they can regenerate from the cut pieces into more fully developed worms.

Prevention and Awareness:

• Inspect and clean gardening equipment and containers to prevent accidental spread.
• Take a picture and report your findings to the iNaturalist website or EDD Maps website.