Hundreds of vibrant magenta or purple flowers standing three to seven feet tall over Apostle Islands wetlands may look pretty, but dig a little deeper into the story of purple loosestrife (Lythrum salicaria) and you’ll understand why this invasive plant poses an ongoing threat.

A single plant can produce a million seeds or more. And left to multiply, these highly aggressive plants from Asia and Europe can choke out native vegetation, leaving wildlife without proper food, nesting grounds, or shelter.

The plants flower from July into the fall. Removing the flower heads before they go to seed is one way to slow the spread. That was the task for eight volunteers from Friends of the Apostle Islands National Lakeshore. They joined the National Park Service on a mission to Long Island on July 24th as part of ongoing efforts to keep the invasive plants in check.

Purple loosestrife is a wetland plant that threatens the numerous high quality wetlands on Long Island. Volunteer Gerry Miller said group members targeted three specific areas. Volunteers used garden sheers or their bare hands to break off the flower heads and filled four very large plastic bags, for disposal on the mainland. Miller said the work was hot, exhausting and satisfying. He said, “For me, getting on the boat, you feel as if you want to get out and help. You want to do something to protect the islands. But it’s also is a social thing. It’s getting out with a group of people who are of like mind and willing to work hard. Yes, it’s work but it’s fun.”

Bagging purple loosestrife flower heads – Julie Van Stappen photo

Beyond removing flower heads, other bio-control methods (which do not use herbicides) include introducing European leaf-eating beetles and and root-mining weevils that consume the purple loosestrife without harming native plants. Miller said the group did see some of the beetles. When they found the insects on flower heads, they shook them off so the beetles could continue to feed on the plants.

Leaf-eating beetle – Gerry Miller photo

Volunteers deep in their work – Gerry Miller photo

The National Park Service has been working to control the spread of purple loosestrife on Long Island since the early 1990s. That’s when Fish Creek Slough in Ashland was a sea of purple and purple loosestrife was found on Long Island. Monitoring plots were established in 1990 to determine whether control methods were working. Hand-pulling was tried for a couple of years but didn’t work so that park needed to look at other options. An IPM (Integrated Pest Management Plan) was completed in 1992 to determine the most effective and least environmentally harmful approach.

In the years that followed, the park implemented a wide variety of methods, including the highly-targeted use of herbicide as well as using specific beetles and weevils, and manual removal of flower heads. A combination of factors, including ongoing collaboration with Tribal partners, lower purple loosestrife levels and the park always looking for the most environmentally safe methods of treating invasive exotic species, led the park to stop using herbicide and to continue to focus on biocontrols.  Monitoring plots established on different parts of the island are being used to measure the effectiveness of these efforts.

Acting Biologist Kasey Arts establishing monitoring plot that will be used to determine the effectiveness of control treatments – Julie Van Stappen photo

This year the park began reintroducing 1,000 Galerucella beetles, root-boring weevil (Hylobius transversovittatus) and flower-feeding weevil (Nanophyes marmoratus) along with removing flower heads to slow the spread. The beetles and weevils feed exclusively on purple loosestrife and do not harm native wetland plants. While volunteers removed flowerheards, park natural resource staff established monitoring plots. The beetle release was done with help from the Northwoods Cooperative Weed Management Area (NCWMA) – a collaboration whose mission is to protect local ecosystems from harmful invasive plants. NCWMA collaborates with tribal nations, local municipalities, state and federal agencies, and non-profit organizations across Ashland, Bayfield, Douglas and Iron counties. You can read more about the Bad River Tribe’s efforts to control invasive species or non-local beings (Bakaan Ingoji Gaa-ondaadag) on their website.

Volunteers sampling blueberries during a break – Gerry Miller photo

The Friends volunteers worked on the island from morning into mid-afternoon. Volunteer trip leader Julie Van Stappen says, “It was a beautiful day and all the volunteers worked hard and had a great attitude, no matter how wet or challenging the hiking. An extra bonus was an occasional taste of wild blueberries along the way. Big thanks to Friends Volunteer Coordinator Jill Rennicke who does a great job organizing and always provides the volunteers with treats. This time she sent along some watermelon, which was perfect on a hot day. And big thanks for the park staff Kasey Arts and Biological Technician Maddie, who did a great job pointing us in the right direction and as boat captain.

Some of the volunteers and NPS leaders take a break – Julie Van Stappen photo

This invasive species mission is part of an effort by Friends and by the Apostle Island National Lakeshore to increase the frequency and range of volunteer opportunities in the park this year. Volunteer Gerry Miller says flexibility is really important if you want to volunteer your time. Already this summer, excessive heat, wind and wildfire smoke have forced delays in some volunteer missions. Rennicke keeps our volunteers in the loop so that when conditions are right, they can make the most of every opportunity.

We thank all of our volunteers for their willingness to answer the call. Thankfully, the weather cooperated for this successful trip to Long Island. We plan additional volunteer opportunities for ongoing maintenance of the historic gardens on Michigan Island and for trail work. If you would like to be added to our list of volunteers, please fill out our online form at this link. Our volunteer coordinator will be in touch.