Hammerhead Worms: Earthworms’ Nemesis
While camping this weekend, my in-laws and I started talking about gardening. My father-in-law asked if I had heard of hammerhead worms that have made their way to the United States. They are eating the good earthworms in our soil. Knowing my father-in-law’s sense of humor, I thought he was pulling my leg. Well, he wasn’t.
Where Did Hammerhead Worms Come From?
In an article on the Alabama Agriculture Extension website, Katelyn Kesheimer states, “Hammerhead worms are native to tropical and subtropical environments. It is likely they hitchhiked to the United States on the roots of horticultural plants and may continue to be accidentally spread across the country on roots or soil of potted plants. Regardless of how they got here, it appears they are here to stay.”
These worms did not just make their way to the United States. They are now an invasive species worldwide.
What Do They Look Like?
The name says it all. These worms have a flat, hammer-shaped head (think hammerhead shark), and their bodies are flat and long. Some species are smaller, about 2-3 inches, while others are larger, up to 8 inches in length.
The worms move like a slug. They then use hair-like organelles to move over the slime that comes from their bodies. They also use the slime as a rope to descend from surfaces.
What Do They Do?
These worms have been called predatory, cannibalistic, horrifying, and ferocious. They mainly feed on our beneficial earthworms.
They secrete a slimy goo containing a neurotoxin, tetrodotoxin. It is the same neurotoxin found in pufferfish. This neurotoxin immobilizes the earthworms. They then use digestive enzymes to liquefy the earthworm. Finally, it sucks out the insides of the earthworm. This neurotoxin also fends off predators.
Where Do They Live?
The hammerhead worms like it hot and humid. They are in the southern United States and prefer wetter climates to dry ones. However, in environments where it is cooler, they survive by getting out of the elements.
Being light-sensitive, the worms seek dark places and feed at night. Their habitats are like our beneficial earthworms, under rocks, leaves, logs, and shrubs. You may even find them hanging in and around your greenhouses.
What If You See One?
If you happen to see one in your garden or yard, you must destroy it. However, please do NOT cut it in half.
These worms reproduce asexually as well as sexually. If only a tiny tip of the worm’s tail is left, the tail grows into an adult worm. Cutting it into sections results in that number of new worms.
First, take a picture of the worm and send it to your local agriculture extension office. These worms are invasive, and they keep a record of sitings.
The Texas Invasive Species Institute recommends capturing the worm and placing it in a jar or baggie. Do not touch the worm. Use a paper towel, stick, or gloves. If you do touch them, worm, wash your hands. Then pour one of the following substances in with the worm. Place the jar/baggie with the worm in it in the freezer for 48 hours to ensure the worm dissolves.
- Citrus oil
- Salt and grain vinegar
- Boric acid (do not use a baggie with boric acid)
- Neem oil
- Insecticidal soap
- Soap water
After the worm dissolves, place the baggie and worm in the trash. If you used a jar, sanitize it thoroughly with alcohol or bleach.
If there is one worm, there are more! Some people go hammerhead worm hunting in their gardens. Be sure to go in the early morning before the sun is up.
Thankfully, some amphibians are making meals out of these worms. Hopefully, the friendly amphibians will help keep their populations in check.
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Hammerhead Worms: Earthworms’ Nemesis
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I’ve always loved gardening and recently started gardening full-time. I also enjoy tending to our chickens, dogs, and other family pets (a bird, a snake, and rabbits).