Purple loosestrife control in Minnetonka
Minnetonka’s purple loosestrife bio-control program expanded in June 2008 with the release of 2,000 loosestrife-eating beetles at a city-owned site south of Minnetonka High School.
Purple loosestrife is a European plant that arrived on the east coast of the U.S. in the late 1800s. The purple-flowering, hardy perennial plant has invaded wetlands in forty states and all Canadian border provinces. Loosestrife has degraded wetlands by choking out native plants resulting in diminished species diversity and wildlife habitat. Bio-control of purple loosestrife began in Minnesota in 1992 and in Minnetonka in 2002. Currently, release projects are a cooperative effort involving the Minnetonka natural resources division, Groveland and Scenic Heights elementary schools and Fortin Consulting.
Biological control of loosestrife involves the release of insects that feed exclusively on the invasive species.
First, loosestrife plants are collected and grown in net-covered pots inside kiddy pools in order to raise loosestrife-eating beetles.
Beetles are then collected from former beetle-release sites and reared under nets in the pools. Once the beetles have mated and multiplied, the plants and beetles are set out in a new location plagued by the loosestrife plant. After seasons of feeding and multiplying, the beetles can cause the plants to quit flowering and decline in size. These conditions do not eradicate loosestrife, but bring it under control, since it is no longer propagating itself.
Beetles have been released in two new Minnetonka wetlands per year for the past three years. This year, the program expanded to include direct transfer of beetles from a collection wetland in South St. Paul to the land south of Minnetonka High School. Pot-reared plants and beetles were released in Big Willow Park as well.
For more information visit http://www.dnr.state.mn.us/invasives/
Beetles are raised, then released to feed on loosestrife.
