Gardeners need to watch out for these 2 worms in Ontario. Here’s why

Click to play video: 'Hammerhead worm that secretes destructive neurotoxin spotted in Ontario'
Hammerhead worm that secretes destructive neurotoxin spotted in Ontario
St. Thomas, Ont. resident Jessica Fugard admits the sight of a Hammerhead Worm in her garden this April was a bit of an eye-opener, having never seen one before. Dr. John Warren Reynolds, a laboratory biologist, says the species is native to Southeast Asia and likely arrived in Ontario via plant nursery stock – Apr 28, 2024

Two potentially destructive worms not native to Ontario have been spotted in the province and an expert says it’s something local gardeners should be on the lookout for.

One worm species is native to Southeast Asia and secretes a neurotoxin that can cause skin tingling or even rashes when touched.

The other is originally from East-Central Asia and can leave soil quality degraded, quickly reproducing and outcompeting the bugs that improve soil quality. Some can even jump as much as a foot into the air.

The 'cannibalistic' Hammerhead Worm

St. Thomas resident Jessica Fugard says she’s no stranger to worms, having handled her share over the years as the daughter of a fisherman.

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But even Fugard admits the sight of a Hammerhead Worm in her garden this April was a bit of an eye-opener having never seen one before.

“At first, honestly, it looked like a leech, because you could see that it was flat (and) it was moving really slow,” she recalls. “When I found it, it was actually eating a snail.”

Characterizing the find as “exciting,” Fugard snapped some pictures and attempted to capture it.

“I went inside … to go find something to grab it with, came back out and it was gone,” she said.

A short video of the worm posted to a gardening Facebook group has garnered close to 4,000 views.

Fugard has since reached out to the Invasive Species Centre (ISC) to get the word out to her fellow growers of the worm’s existence.

“It’s not every day that you get to discover something … that should be talked about.”

To date, the ISC has seen about a half dozen reports of hammerhead worms across the province, which includes discoveries in Hamilton, Newmarket and Woolwich.

Dr. John Warren Reynolds, a laboratory biologist who has been studying worm species for over 55 years, says the hammerhead is considered invasive in some regions of the world where they’ve turned up.

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Also known as bipalium or broadhead planarian, the hammerhead does have a line that creates which produces a neurotoxin known to be destructive to nerve tissue.

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Reynolds says the chemical, typically found in worm slime, can cause human fingers to tingle or even breakout in a rash when touched.

The effects on pets and children can be a little more profound if eaten, often resulting in hospitalization.

“If you mistakenly ingest some or part of it … they can make you nauseated, but they aren’t necessarily fatal,” Reynolds explained.

The species’ destructiveness is more apparent in the ecology since the predator attacks useful earthworms, slugs and snails.

“They’re also cannibalistic, so if they don’t find those other things, they can eat other worms if they find them,” said Reynolds.

Gardeners who run into one should don a pair of gloves and grab the pest storing it in a plastic bag and leaving the catch in the blistering sun.

Typically, the species can be eliminated when exposed to temperatures of 40 C (104 F).

Reynolds says there’s no magic spray to eradicate the worms and cutting them up solves nothing as the hammerhead can regenerate and even multiply.

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“The interesting thing about this group of worms is if you chop them up into a dozen pieces, each piece will grow into a new individual,” according to Reynolds.

Asian Jumping Worm may be bigger problem

Another worm that’s been spotted in higher numbers across the province is the Asian Jumping Worm, which Reynolds suggests may be a bigger problem than the Hammerhead.

With a very distinctive wild thrashing movement when threatened, the jumping worm can reproduce more quickly than other earthworms and consume organic matter leaving behind a dry and granular material, much like coffee grounds.

Reynolds says the pest’s leavings can degrade soil quality and potentially choke out native plant species.

“They’re so aggressive that they can outcompete the native bug … the ones that are doing the good things in your garden.” Reynolds said.

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This July 2, 2014, image provided by Susan Day shows a mature Asian jumping worm found in Madison, Wis. The species is distinguishable from other earthworms by the presence of a creamy gray or white band encircling its body. (Susan Day/UW–Madison Arboretum via AP).

Reynolds says the jumping worms can be between two to eight inches in length and have a smooth, glossy grey or brown appearance.

The clitellum, a distinctive band on most earthworms’ bodies, is another way to identify them.

The ring completely encircles the body of the worm, where on a typical European earthworm, the clitellum is raised and does not completely encircle its body.

“They come in a variety of iridescent colours … and they move like snakes, and some of them could … jump almost a foot high,” said Reynolds.

Nursery stock likely bringing in the worms

Halton Region’s Master Gardeners of Ontario (MGOI) have been alerting members and the general public about both worms over the past year, suspecting they’re coming into the Province via the nursery trade.

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David Dutkiewicz, an entomology technician at the ISC, says researching planting purchases is key to keeping invasive pests and plants from potentially wiping out a garden.

He suggests finding native alternatives to some of the more easier accessible imported plants and thoroughly checking out the bottom of every shrub.

“It’s always a good practice to remove the root ball from the pot to sort of give them a once over,”  Dutkiewicz submits. “You want to spread the roots out anyways … so that the roots will actually start to grow better.”

Reynolds concurs believing worm cocoons hiding in stock with a burlap covering could be what is introducing the worms into the ecosystem.

“We stress that if you’re going to get nursery stock, get bare root because that way you can see that there’s nothing there,” he says.

Both Reynolds and Dutkiewicz encourage Ontarians to report worm sightings to the ISC or on

Ontario’s Ministry of Natural Resources and Forestry (MNRF) recommends residents report sightings online via a tracking system that receives funding from the provincial agency.

At present the ministry does not regulate the species in Ontario, under the Invasive Species Act, 2015.

“The ministry does not actively collect data on hammerhead worms in the province,” MNRF spokesperson Marcela Mayo said in an email.

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“Therefore, we are unable to confirm presence of this species in the province.”

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