Hammerhead Predatory Worm Migration and What You Can Do About It

According to an article written by The Daily Journal online about hitchhiking predator worms, we need to be on the lookout for their migration, especially because of the danger they pose to our friendly earthworm.

The Hammerhead Predatory Worm (Bipalium sp) is an invasive predatory worm species that came to the US from Southeast Asia. It is believed to have arrived in other countries, including the US, in the soil of nursery plants. It gets its name because the head of the worm looks similar to the head of the hammerhead shark. The ones in the US usually have a dark horizontal stripe down its side. 

Due to the heat and humidity of their natural habitat, most Hammerhead worms are found in southern states. Although they are well established in Louisiana, Texas and Florida,  they were not believed to be in the central United States.  However, one as long at 1 ft. was recently found as far north as Springfield, MO.

Besides the horrifying appearance, what makes these worms such a pest is that they are incredibly carnivorous. They have a voracious appetite for any kind of invertebrate.  While they will feed on any insect, they are especially fond of phylum Annelida, better known as earthworms. It has been said they can track earthworms underground where they kill and eat them.

To make matters worse, the hammerhead worm emits a mild neuro-toxin that paralyzes their prey. It then spits out juices that partially digests and liquefies its victim. Then it consumes the liquid and immediately begins hunting again. Wherever it goes, it leaves a slime trail like a slug, which, by the way, is also on its menu.

Because they are an invasive species, and we are currently unaware of the effect they have on soil fertility and nutrient cycling, it is recommended that you kill them when found. However, you can’t just cut them into pieces. The pieces will regrow a new head and any organs they need. If you cut it into three parts, you will end up with three worms. They are asexual and multiply by tearing off its tail, allowing it to regrow a new head and organs. It sounds like something from a horror movie if you ask me.

Although currently there are no known controls to target the Hammerhead Worm, and they seem to survive freezing temperatures, gardeners can rid the soil of them by heating it to 93ºF for five minutes. Otherwise, these predators are something we will have to live with. 

Fortunately, from all current indications, it poses no threat to humans or pets but is most definitely a danger to native earthworms and beneficial insects. I won’t personally test that theory.

What I would suggest, as in any situation when you are fighting soil pests, is to place high importance on increasing a healthy environment in your soil.  With earthworms being so beneficial to the soil and subsequently the health of your turf, working to increase beneficial microorganisms is a must. Check out this article on how important Organic Matter is as a food source for microorganisms and how to know the right amount needed for your soil.

Russ James
AgriGro Turf Specialist

Sources:
“Hitchhiking hammerhead worm kills native earthworms” by Daily Journal Online,  Jul 13, 2020, Updated Jul 28, 2020