Officials warn public not to touch invasive hammerhead worm: 'Silent assassin' By Erin Feiger, Residents in Ontario, Canada, are being advised to remain vigilant for the return of the toxic hammerhead worm this spring. InsideHalton.com reported that this crawling creature — referred to as the "silent assassin" — has been spotted in London and Hamilton. According to the Hamilton Conservation Authority, hammerhead worms are a toxic, non-native species that first appeared in Ontario in 2017. They are believed to have arrived in North America via the introduction of plants from Southeast Asia. The term hammerhead worm encompasses various species of flatworms, also known as shovel-headed garden worms, which is a fitting description of their shape. They can grow between 5 and 10 centimeters in length and may exhibit multiple colors. They are also toxic, releasing a neurotoxin called tetrodotoxin — the same substance found in pufferfish. While not fatal, this toxin can cause skin and eye irritation in humans and can be harmful to pets if ingested. Hammerhead worms reproduce both sexually and asexually, producing an egg capsule that hatches in about 23 days, yielding up to eight offspring. They also have no natural predators, so controlling their spread is the best way to mitigate their damage. Hammerhead worms eat earthworms, snails, and insects. Reducing the population of native species, like earthworms, can negatively affect soil health and nutrient cycling. If you come across a hammerhead worm, experts recommend using a covered hand, a stick, or a small shovel to pick it up, then placing it in a sealed container with soapy water or vinegar and salt. Dispose of them in the sealed container.