Credit: Rob Routledge, Sauk College, Bugwood.org
Pale swallow-wort (Vincetoxicum rossicum), an invasive vine, has been found for the first time in Wisconsin. The populations straddle the boundary between Oconto and Shawano Counties, and the Timberland Invasives Partnership is actively managing these infestations.
We encourage you to learn how to identify pale swallow-wort and look for it in your woods, especially if your woods are in or near Oconto and Shawano Counties. Early detection makes management much more effective and cost-efficient.
Pale swallow-wort is a perennial plant that dies back to the ground each year (it’s herbaceous). A related invasive species, black swallow-wort, has been present in Wisconsin for many years and is not widespread, but it is a concern, too.
Pale and black swallow-wort are in the milkweed family, and monarch butterflies have been observed laying their eggs on these plants—but the caterpillars then die because they can’t eat swallow-wort. Both species of swallow-wort form dense infestations that outcompete native plants.
Summer is the best time to identify pale and black swallow-wort because they flower in June and July. If you find either species of swallow-wort, please report it by emailing invasive.species@wisconsin.gov with the following:
- Location (address or coordinates)
- Clear photos (ideally of the flowers)
- Size of the population
- Habitat type (optional but encouraged)
- Property ownership (optional but encouraged).
Alternatively, you can submit a report via EDDMapS on the computer or the phone app.
