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Purple loosestrife biocontrol — and you

Purple loosestrife, an exotic plant from Europe, has overrun many state wetlands.

Wisconsin DNR has been using four of its insect enemies, also from Europe, to control it here since 1994. Careful research has shown that all four control species depend only on loosestrife and do not threaten native plants. This is classic biocontrol, and it is likely the best long-term control for loosestrife, reducing the need for other more costly and disruptive controls, such as herbicides.

Two "Cella" beetle species (Galerucella calmariensis and G. pusilla) feed on its leaves and shoots and are the most effective of the four types of imported insects. Cellas monitored in the state and elsewhere have decreased the vigor, size and seed output of purple loosestrife, allowing native plants to survive and increase naturally by competing better against smaller loosestrife plants.

The length of time required for effective biocontrol in any particular wetland typically ranges from one to several years, depending on such factors as site size and loosestrife density. Though loosestrife elimination is rare, this process offers effective and environmentally sound control of the plant without herbicides.

You can help control purple loosestrife

Cellas need to be released wherever purple loosestrife grows to keep it in check. Since 1997 hundreds of volunteers across the state have shared in the fun of rearing Cellas and releasing them into local, infested wetlands. Raise beetles in your backyard or schoolyard on caged, potted loosestrife plants starting in spring, and take the pots to local infested wetlands for release in summer. The program offers free equipment and starter beetles to all state citizens who want to take part.


Help UW Madison Division of Extension Natural Resources Institute’s Aquatic Invasive Species Program evaluate our training videos and their use by taking this survey after you watch this and other videos in the series: Purple Loosestrife Training Follow Up Survey. You can repeat the survey for each of the videos in the survey or watch multiple videos and reply for all of them at once.


Educational materials for students:

  • See Cella Chow! Here you’ll find lesson plans for grades 6-12 built around the science of biocontrol, specifically purple loosestrife. The lessons include a listing of the related Wisconsin Model Environmental Education and Science Standards.

Purple loosestrife is here to stay in Wisconsin, but you can help protect your wetlands from domination by this exotic invader by simply reuniting it locally with its natural predators! And as biocontrol reduces your loosestrife, you'll experience even more satisfaction by helping to restore any native plants the loosestrife may have eliminated locally, further ensuring diverse, healthy wetlands!

How to volunteer

For more information, or to volunteer, please contact:

Purple Loosestrife Biocontrol Coordinator
Purple Loosestrife Project
101 S. Webster St., WY/4
PO Box 7921
Madison, WI 53707-7921

Training Opportunities

To find learn if there is an upcoming training near you, contact the program coordinator or your county Aquatic Invasive Species Coordinator. The County Coordinators can be found at Wisconsin DNR AIS Contacts. Some counties may not have a coordinator, but there could be training in a county nearby.