Hammerhead worms are native to Asia, particularly Southeast Asia, but have become invasive in many other parts of the world, including the United States and Canada. In the U.S., they have been found in a wide range of states, primarily favoring warm, moist environments. Their presence has been documented in the Southeast (including Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Texas), along the East Coast, and on the Pacific Coast (California). They have also been spotted as far north as New York and in other states such as Virginia, Maryland, New Jersey, Ohio, Oklahoma, Missouri, Arkansas, and Arizona. In Canada, hammerhead worms have been found in Ontario, including areas like Dundas Valley and Cootes Paradise
. These worms thrive in moist organic matter such as leaf litter, wet mulch, garden beds, soil, under logs or rocks, and greenhouses. They avoid hot, dry areas and are mostly active in cool, damp locations, often moving and feeding at night
. Their spread in new regions is largely attributed to human activity, especially through the horticulture trade, where they are transported in soil of potted plants and gardening materials
. In summary, hammerhead worms are found:
- Native: Southeast Asia (also reported in Australia, Africa, South America)
- Invasive in the U.S.: Southeastern states, East Coast, Pacific Coast, and some northern states including New York
- Invasive in Canada: Ontario, including natural areas like Dundas Valley
- Habitats: Moist soil, leaf litter, gardens, forests, greenhouses, under rocks and logs
They prefer warm, moist environments and are commonly found in gardens, forests, and agricultural fields where they prey on earthworms and other soil invertebrates
