The ice ages are thought to have destroyed native earthworms wherever glaciers covered land; hence, virtually all species in Canada are probably introduced from Europe, often by humans, or reintroduced from unglaciated areas of the US. Earthworm distributions are mainly limited by soil moisture.
Also, where are worms native to?
Thousands of years ago, glaciers that covered North America and reached as far south as present-day Illinois, Indiana and Ohio wiped out native earthworms. Species from Europe and Asia, most likely introduced unintentionally in ship ballast or the roots of imported plants, have spread throughout North America.
Where do worms come from?
Europeans added soil, with its earthworms or worm cocoons, to ships for ballast. Once anchored in North American harbors, ships released their ballast -and living worms, who found new homes. A. Earthworms eat dirt! Their nutrition comes from things in soil, such as decaying roots and leaves.
Are worms invasive?
Earthworms are invasive species throughout the world. Of a total of about 6,000 species of earthworm, about 120 species are widely distributed around the globe. These are the peregrine or cosmopolitan earthworms. Some of these are invasive species in many regions.