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See how you can help raise special beetles to feast on this plant and protect wetlands.

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Purple loosestrife biocontrol

There are a number of methods to control purple loosestrife, however biocontrol may be the most viable long-term control method, promising to greatly reduce the need for other more costly and disruptive control methods.

The DNR and University of Wisconsin-Extension (UWEX), along with hundreds of citizen cooperators, have been introducing natural insect enemies of purple loosestrife, from its home in Europe, to infested wetlands in the state since 1994. Careful research has shown that these insects are dependent on purple loosestrife and are not a threat to other plants. Insect releases monitored in Wisconsin and elsewhere have shown that these insects can effectively decrease purple loosestrife's size and seed output, thus letting native plants reduce its numbers naturally through enhanced competition.

A suite of four different insect species has been released as biological control organisms for purple loosestrife in North America and Wisconsin. Two leaf beetle species called "Cella" beetles that feed primarily on shoots and leaves were the first control insects to be released in Wisconsin, and are the insects available from DNR for citizens to propagate and release into their local wetlands. A root-mining weevil species and a type of flower-eating weevil have also been released and are slowly spreading naturally. The Purple Loosestrife Biocontrol Program offers cooperative support, including free equipment and starter beetles from DNR and UWEX, to all state citizens who wish to use these insects to reduce their local purple loosestrife.

The length of time required for effective biological control of purple loosestrife in any particular wetland ranges from one to several years depending on such factors as site size and loosestrife densitys. The process offers effective and environmentally sound control of the plant, not elimination in most cases. It is also typically best done in some combination with occasional use of more traditional control methods such as digging and herbicide use.

Though purple loosestrife is almost certainly here to stay in Wisconsin, we should be able to efficiently protect our wetland ecosystems from domination by purple loosestrife by simply restoring some of the natural checks and balances that can result in diverse, healthy environments.

Purple loosestrife fact sheets

Volunteer opportunities

You can be part of this solution. Learn more about the Purple loosestrife biocontrol program and how to Acquire biocontrol beetles for your loosestrife infested wetlands. To join the program, download this application.

How to volunteer
For more information, or to volunteer, please contact:
Brock Woods
Purple Loosestrife Project
DNR Science Operations Center
2801 Progress Road
Madison, WI 53716
Last revised: Friday May 22 2015