Cottage gardeners beware—these two worm species are trouble
Cottage gardeners beware—these two worm species are trouble
Cottage country gardeners should be on the lookout for troublesome worms wiggling their way—uninvited—into garden beds. Hammerhead worms (Bipalium adventitium) and jumping worms (Amynthas spp.) seem destined to be the stars of a Hollywood horror movie thanks to their unsettling looks and behaviours. But it’s their negative effects on the environment that are the real cause for concern.
Hammerhead worms tend to scare people because they can grow to be one to three feet long, says John Warren Reynolds, PhD taxonomist and director of the Oligochaetology Laboratory in Kitchener, Ont., which conducts and publishes research on earthworms. Originally from Southeast Asia, hammerhead worms secrete a neurotoxin similar to what’s found in pufferfish, so people should avoid handling them with bare hands, Reynolds says. Touching the worms without gloves can produce a rash or tingling feeling, but you can stave off the effects by washing your hands thoroughly after handling any worms.
Hammerhead worms can turn cannibalistic if they can’t find enough of their preferred diet of earthworms, slugs, and snails. And like the hydra, a mythical two-headed monster that could regrow its heads after being decapitated, the hammerhead worm can regenerate from cut sections of its body. If you chop a hammerhead worm into a dozen pieces, each piece can grow into a new one, says Reynolds. In contrast, if you cut an earthworm in half, you might get one regenerated earthworm.
It’s these adaptations that make the hammerhead worm a formidable invader. “Essentially, you’ll never get rid of them. They’re here to stay,” says Reynolds, adding that the worms are considered invasive. He says hammerhead worms have lived in North America for over a century and in Canada for a number of decades, but they’ve been popping up more often in recent years.
Unnerving as the hammerhead worm may be, jumping worms (Amynthas spp.) are a far greater threat to the environment. These invasive earthworms are native to Asia and have spread throughout the United States and, now, Ontario, New Brunswick, and Nova Scotia. As their name suggests, jumping worms are infamous for their strange thrashing and jumping behaviour when disturbed.
Jumping worms “totally destroy” the leaf litter layer in forests, says Reynolds. They ingest leaf litter and churn out worm poop that looks similar to coffee grounds. The result is less desirable for plants, Reynolds says, and can lead to erosion and reduced habitat for animals like ground nesting birds.
Both hammerhead worms and jumping worms are primarily spread by humans, says Reynolds. “They do not move far by themselves.” Invasive worms can spread through the plant nursery trade, but gardeners can do their part to stop these critters by purchasing bare root plants that can be checked for worms. The worms also reproduce via tiny, egg-filled cocoons, which are smaller but can still be seen. To avoid transferring these, wash your tools, boots, and vehicle wheels when moving from one field or garden site to another, says Reynolds.
If you come across a hammerhead worm, Reynolds advises safely euthanizing the invasive by placing it in a sealed plastic bag and leaving it out in the sun. The bag can then be tossed in the garbage. For jumping worms, Reynolds says he’d love to see them for research purposes, and encourages folks who come across the critters to get in touch with him.