Invasive hammerhead worm appears in Darke County


By Taylor Dill

OSU Extension Darke County

DARKE COUNTY — The Ohio State Extension office has received calls and questions about a new to Ohio species of worm found here in Darke County. The type of worm that has been found is a Hammerhead Worm. This type of worm is a species of terrestrial flatworms. These species are shiny and covered in a slime-like substance. However, these flatworms do not have the tentacles that slugs have. They also have a crescent shaped head and can be up to 12 inches long. The Hammerhead species are usually orange, yellow, or brown with one to several stripes along the back. Flatworms in general are more common in southern states, such as North Carolina and Florida, where these species can be native or were introduced from another country before 1950. Hammerhead worms have moved throughout the country through the movement of soils, especially in greenhouse production.

Hammerhead worms require moisture, so they can be found under rocks or other debris where the environment stays wet and humid. Flatworms in general are predatory. They feed on invertebrate organisms like earthworms, snails, slugs, and arthropods. Flatworms’ mouths are on the underside of the body towards the middle. Similar to a snake, flatworms wrap around their prey to consume it.

Flatworms can reproduce asexually; this occurs when the body is divided, and each section becomes a new worm. Therefore, cutting these worms up to destroy them is not an effective tactic. This is one reason why these worms can become abundant so quickly in an area. Because this species can populate quickly and consume earthworms, they can be considered damaging to the environment. However, the impact on the environment is complicated and not well understood or measured. They are likely not a major concern as no direct evidence of their impact has been seen in the areas that they inhabit now. However, the main human health concern is that this species contains the same toxin that is in puffer fish and is used to assist them in overcoming prey. The worms contain low quantities of the toxin, but it can cause irritation if it is touched with bare skin.

If you find these in your yard or garden, do not try to dispose of them by cutting them up, as that will only produce more. You can destroy these worms by placing them in a bag with tweezers or gloved hands and freezing them, or by using rubbing alcohol. To avoid direct contact, use salt to eliminate individual worms. Limit salt use near plants. Molluscicides and traps can be effective against flatworms as well as slugs, but keep in mind, these management strategies will also eradicate earthworms.

These worms have traveled through the United States in potted plants and through greenhouse production. If you find a flatworm in a potted plant or in soil, try not to move or plant it without first isolating and destroying the worm. Though, it is assumed there is minimal damage to the environment associated with these species, it is best to avoid moving them around since they are considered invasive.

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