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Eurasian watermilfoil (EWM) is an aquatic invasive plant that can cause a lot of problems once established in a lake. One non-chemical method controlling EWM is biological control. Using the Milfoil Weevil (Euhrychiopsis lecontei) is one of these methods.

In 2011-2014 we conducted a pilot study to test whether volunteers could successfully raise their own weevils on a mass scale. Read more about the mass rearing method in Chapter V of our Biocontrol Manual.


Even simpler and cheaper:  What if we could allow the native weevil population to reproduce naturally in the lake with no predators picking them off?  Our latest experiments tested the efficacy of predator exclusion cages in Lake Joanis, Schmeekle Reserve, Stevens Point.  From 2016 - 2021, we monitored how the weevils do when fish predation is not an issue - no weevil stocking required!  GET THE REPORT.   See the full Lake Joanis EWM HISTORICAL SUMMARY.

Want to know more about weevils?  Our biocontrol manual has pretty much everything you want to know about weevils... whether you're a lake resident or a lake management professional. Get the pdf below.

Eurasian Watermilfoil
Biological Control Research

Purple Loosestrife is a perennial wetland plant that can quickly colonize new areas and can become the dominant species in that area. These dense patches of purple loosestrife decreases nesting quality, resulting in decreased waterfowl and shorebird populations.

There are multiple control methods of purple loosestrife, including manual removal of small populations, herbicide application, biological control, or a combination of these methods.

The biological control project consists of using two "Cella" beetle species, Galerucella calmariensis and Galerucella pusilla. These beetles originate from Europe and feed specifically on Purple Loosestrife, meaning they do not harm native plant species. 

This biological control is considered to be the best long-term control for Purple Loosestrife. Cella beetles have been monitored throughout the state showing a decrease in plant size, seed abundance, and increase in native plant growth.

Want to learn more about Purple Loosestrife biocontrol? Click the BIOCONTROL PLANNING button below or Click Here to visit the DNR website. Want to help raise Cella beetles? Visit our Volunteer page to contact us.

Purple Loosestrife Biological Control

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