My youngest daughter was playing outside, rolling over logs and railroad ties trying to find bugs to catch, when she discovered a funny looking worm. She studied it for a minute, and then brought it to me in great excitement.
“Mommy! Look at this funny worm I found!”
I was just as fascinated as she was. As it inched along, it stretched from just a couple inches to nearly six inches long! What a strange worm, I thought. It’s head resembled that of a hammer-head shark.
Of course I set straight to researching what it was. Not really knowing what to look up, I googled “hammerhead worm”. Sure enough, Wikipedia has a whole article devoted to Bipalium, loosely referred to as the “hammerhead worm”.
What I found out next wasn’t so exciting.
Hammerhead Worms Fun Facts
|Latin name||Bipalium species|
|Diet||Carnivorous (it eats earthworms)|
|Size||Around 8 inches (20 centimeters)|
What Are Hammerhead Worms?
The hammerhead worm, the full name of which is Bipalium kewense, is a hammerhead flatworm or land planarian. Its head looks just like a hammerhead shark, as I mentioned. These worms are massive, with some growing to 20 inches long. Most, however, will only grow to about an inch – at least that’s a nightmare to save for another day!
Hammerhead worms secrete thick, dense mucus from their undersides as they move. Some hammerhead worms have stripes, but others do not. They can be found in shades of black, gray, orange, or brown. Sometimes, you might hear hammerhead worms referred to as shovelhead or arrowhead worms. They are frequently found in caves.
Hammerhead worms are often called hammerhead slugs. To be fair, they look a lot like slugs as they move in a slug-like fashion. The cilia on their creeping soles help them glide, and they leave behind a thick string of mucus just like slugs, too.
Although they’re harmless to people, they can be devastating to a garden. Hammerhead worms are considered an invasive species. They prey on earthworms, and can completely decimate a garden if they aren’t taken care of.
Supposedly, if you try to squish them or cut them they’ll multiply and grow into more worms. And other animals don’t like to eat them because they secrete a foul tasting slime.
Great. Another garden pest to worry about.
However, it’s important that you take the time to worry about them. Earthworms are so crucial in any garden because they help fertilize and aerate the soil. Without them, you won’t have much of a garden. Hammerhead worms, particularly a severe infestation of hammerhead worms, can completely ruin you garden’s success.
Hammerhead worms aren’t toxic to people, but they are toxic to other creatures because of their neurotoxins.
That being said, while it’s perfectly safe to touch or interact with a hammerhead worm, we don’t recommend you eat them these planarians contain tetrodotoxin, the same kind of toxin found in pufferfish, rough-skinned newts, and blue-ringed octopus.
It’s not known whether these toxins would produce similar ill effects in humans if ingested – but don’t try it!
What to Do About Hammerhead Worms
As I mentioned, you can’t get rid of hammerhead worms by squishing or cutting them. They will regenerate into new worms when you cut them into pieces, so you will only make your problem worse by reacting with this sort of violence!
They are hermaphrodites, with each worm possessing both types of reproductive organs. The worms reproduce via fragmentation, leaving behind a tail tip stuck to a leaf which then turns into an adult. It only takes a few weeks for the pieces to regenerate, and injured worms can easily repair and produce new tissue.
The best way to kill hammerhead worms is to fill a spray bottle with citrus oil. This is often sold in the cleaning aisle at your local grocery store, although you can also make your own at home.
Here’s the deal – you can’t kill hammerhead worms by simply spraying citrus oil in your general garden area. You have to spray each and every worm until your population is dead.
Designate a certain day of the week – and a time – to spend in “hammerhead hunting.” Go out first thing in the morning, ideally after a heavy rainstorm when the worms will rise to the surface of the soil. Spray the worm until it is completely soaked in citrus oil. If the worm is on a plant or leaf, knock it on the ground so you don’t hurt your plant.
You can spray with citrus oil as often as you’d like, but keep in mind that you will need to do this at least once a week to control the population. If you’re unsure of whether you’ve killed off all the hammerhead worms, check for eggs. These look like tiny black or red cocoons – the cocoons will be filled with eggs. These should be removed and destroyed immediately.
If citrus oil doesn’t seem to be doing the trick, you can also try using vinegar or salt. These, like citrus oil, need to be applied directly to the hammerhead worm in order to be effective. Use a spray bottle or simply pour the ingredients directly on top of the worms to dissolve.
Don’t think you’re immune just because you live in a cold environment, either. These creatures can establish themselves in a greenhouse and disperse quickly into the surrounding area. In a cold climate, they can survive freezing and below freezing temperatures by hiding out in protected locations.
We’ve been collecting them in a jar and sprinkling salt over them, which kills them very quickly. I’m afraid to try feeding one to my chickens ’cause if they peck it into two pieces and one gets away it might just turn into a whole new body.
I thought I’d share so you guys can be on the lookout for hammerhead worms around your home and garden. If you find one, sprinkle it with salt or drown it in a jar of water.
This is the first I’ve ever seen or heard of hammerhead worms. Have you ever seen one? Are they a problem in your garden? Be sure to pin this article to your Pinterest so you know where to look should this pesky pest ever pay you a visit.
updated 10/29/2019 by Rebekah White
A city girl learning to homestead on an acre of land in the country. Wife and homeschooling mother of four. Enjoying life, and everything that has to do with self sufficient living.