Purple Loosestrife

Purple loosestrife (Lythrum salicaria) is a wetland invasive plant often noticed in late summer because it’s so easy to see in bloom along roadsides, on river and lake shorelines and in wetlands. Not to be confused with a beautiful and important native, swamp milkweed (Asclepias incarnata), which is also blooming now! The colors may be almost identical, especially when viewed in large patches from a distance or while moving at 70 mph along the highway. Purple loosestrife’s flowers are spires (pictured on the left), but flowers of the milkweed are rounded and flat-topped umbels (pictured in the circle on the right). The WDNR welcomes reports for purple loosestrife at invasive.species@wisconsin.gov.


This summer, the Douglas County Natural Resources Specialist / AIS Coordinator worked with partners to raise and release 23,000 Purple Loosestrife biocontrol beetles.  Raising these helpful beetles is part of an approved biocontrol program going on across Wisconsin, and they are out in wetlands in Douglas County right now eating Purple Loosestrife plants to help reduce and control the invasive populations in our area.

Swamp milkweed vs purple loosestrife-JScherer 2022
  • Purple Loosestrife Project - This Wisconsin DNR project works with citizens and students to raise beetles that feed on the purple loosestrife plant. Contact: Dara Fillmore | (715) 392-7825 | E-mail