There could be a new horror lurking in your garden in the form of a particularly dangerous little worm, and this creepy crawly is trouble on multiple levels.

Known as Bipalium, or hammerhead worms, this genus of sizeable predatory landworm is considered invasive in North America, and the species Bipalium adventitium has been present in Ontario since as early as 2019, feasting on defenceless earthworms and threatening havoc on local garden ecosystems.

Something I didn't expect to see in our #Ontario #garden! Bipalium adventitium is an invasive Asian species of terrestrial #planarian ("flatworm") that preys mostly on earthworms. Often called "hammerhead" worms, some tropical forms are up to a metre in length! #WormWednesday pic.twitter.com/RQ02XH21pF

— Dave Rudkin (@RudkinDave) September 25, 2019

Identifiable by its namesake hammer-shaped head and distinct reddish stripe, B. adventitium lurks in gardens, using chemoreceptors to track the chemical trail left by victims.

Once a hammerhead worm finds its unsuspecting prey (earthworms have not developed a natural defence against these invaders) it wraps its body around the victim to prevent escape and finishes the job by stabbing the earthworm with an everted pharynx (like the stabby mouthparts from the Alien film franchise).

Rebecca Morton of Toronto-based Armour Pest Control tells blogTO that while these worms are still uncommon, "they have been spotted in gardens through the GTA over the past few years."

"Whenever we have an invasion of insects that are non-native to our environment, we worry mostly about how it will affect the natural habitat. The biggest threat these snake-like insects pose is to earthworms, which are their preferred food source. Earthworms are integral in maintaining our soil health and biodiversity."

If that wasn't horrifying enough, the species of hammerhead worm present in Ontario was recently confirmed to contain tetrodotoxin, a potent neurotoxin found in notoriously deadly animals like the pufferfish and blue-ringed octopus.

While it is currently unknown whether this toxicity evolved to deter predators or assist in subduing the worms' prey, it makes these worms incredibly dangerous to handle.

Morton warns anyone who comes across a hammerhead worm that the neurotoxin "can irritate human skin if touched and make pets sick if ingested."

She explains that "If seen, it's critical to catch them without contacting bare skin and killing them with salt, vinegar, or neem oil. Then disposing of them in a sealed container."

Morton stresses these natural methods of pest management, cautioning that "It's extremely important not to treat gardens or other outdoor areas with insecticides that are not approved for this use, as they can contaminate the soil and harm non-target insects that are necessary to maintain our environment."

So if you see one of these potentially dangerous critters, make sure to keep pets clear and put your best killing face on.

Just be sure to dispatch these worms with extra care and avoid coming into contact with their neurotoxins.