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A view of the marsh before the beetles were released.
After just two seasons, native plants are returning to the marsh.
The Galerucella beetle munches on the leaves.
Beetles were released into the marsh filled with purple loosestrife.
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The Problem
Purple loosestrife is a beautiful but aggressive, invasive plant. It originally was introduced into eastern North America from Europe in the 1800s as an ornamental plant. Since then, it has spread over much of the U.S. and Canada.
It is a hardy perennial plant, which can rapidly overtake wetlands, displacing many native wetland plants. When it does so, those wetland habitats, where many fish and wildlife feed, seek shelter, reproduce young, quickly become choked in a sea of purple flowers that do not provide wildlife with needed food and shelter. Purple Loosestrife thereby degrades wetlands by diminishing their value as wildlife habitat.
One of the last remaining wetlands on the Lower Fox River has been overtaken by Purple Loosestrife. The Green Bay Metropolitan Sewerage District (GBMSD) and Wisconsin Public Service Corporation (WPSC) who own parcels of the wetland, initiated a collaborative project in 2000 to control Purple Loosestrife biologically.
The Solution
Biological control was selected as the most appropriate control strategy for this wetland site. Biological control uses predatory insects to control the spread of Purple Loosestrife. Five species of beetles have been approved by government agencies as biological control agents for Purple Loosestrife, and therefore they can be used without fear of negative impacts to native North American plants. Two species of Galerucella Beetles, which are leaf and flower feeders, were selected for this project.
The Project
GBMSD and WPSC teamed up with the De Pere High School Ecology Club and Bay Beach Wildlife Sanctuary to conduct a Purple Loosestrife control project in the wetland during 2000 and 2001 using beetles.
Late each spring, a few adult Galerucella Beetles were placed on Purple Loosestrife plants that had been potted a few weeks earlier. Nets were placed over those host plants to prevent the beetles from escaping.
The adult beetles laid eggs on the host plants and several weeks later those plants were crawling with hundreds of beetle larvae. The host plants were then taken to the wetland where the nets were removed and the beetle larvae were released to start a population there.
Before beetles were released, the wetland was overrun with Purple Loosestrife. Now, Purple Loosestrife has been controlled and native plants again florish.
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