The Beetle That Saved the Wetlands

        Once upon a time, long ago in a land far away, a beautiful purple-flowered plant bloomed every summer.  It attracted bees and other pollinators and was used for medicine and to make gardens pretty.  It was well-behaved in its native land, never overstepping its bounds, because a tiny beetle that wouldn’t eat anything but the purple-flowered plant’s leaves kept it in check.  The beetles knew to eat just enough of the lovely plants that they were satisfied, but left enough so that there would be food for future years.

        Then, in the early 1800s, the people who grew the purple beauties decided to cross the ocean and move their families to the United States of America.  Along with their precious household items, they brought along some of the purple-flowering plants from their gardens to help them feel at home in their new land.

        But they never thought to bring along the beetles.  The beetles were okay with that; there were plenty of the plants left behind so they were happy to stay home and munch away.  The purple-blooming plants that made the ocean crossing were ecstatic!  “No more beetles chewing away at us!” they said.  “We’ll be kings of the garden!”

        And they were.  Everybody in the New World wanted the purple lovelies in their gardens, and the plants found new homes everywhere. 

        One day, one of the purple bloomers found itself growing next to a marsh.  “Hey!  This looks like a great place to grow.  I think I’ll toss some of my seeds into this marsh and see what happens.  After all, I can make TWO MILLION seeds every year so I’ve got plenty to spare.” 

        It turned out great!  In just a few years, the purple-flowering plant was the only thing growing in the entire marsh.  Every summer, there was a sea of purple as far as the eye could see.  And that was just the beginning.  Over the next two hundred years, the purple bloomer found wetlands and ditches to overrun in every state in the Union and most of Canada’s provinces. 

        Sadly, it took almost 200 years after the plants arrived in the New World for people to get wise to its evil plan.  When they finally noticed that there were too many purple-flowering plants, they began frantically trying to reign it in.  They tried cutting it, but it just grew back.  They tried pulling it, but its large woody taproot made pulling it really hard work.  Plus the broken roots and stems accidentally left behind just grew into new plants.  Then they tried killing it with poison.  That’s never a good idea near water.  Other plants nearby that had somehow survived died from the poison too.  And so did some fish and other aquatic animals and insects.

        What to do???  Finally, somebody had the bright idea to bring some of the beetles from the Old Country to the United States to feast on the plants.  It was a long process, though.  Scientists wanted to make sure that the beetles wouldn’t eat anything other than the leaves of the purple-flowering plant.  Because if they did, they might wipe out the population of something valuable to our ecosystems or even some important food crops.  So they kept the beetles contained while they offered them a wide menu of plants to see if they would bite.  After years of testing, scientists determined that there was only one thing on the menu for the beetle called galerucella and it was the purple-flowered plant.

        It began to look like the purple-flowered plant wasn’t going to live happily ever after in the New World after all!

        Purple loosestrife arrived in Wisconsin in the early 1900s.  It is an aggressive woody perennial plant that grows two to seven feet tall.  From July through October, it displays tiny. bright purple flowers closely attached to four-sided spiky stems.   Some plants have up to fifty stems, making for a bushy look.  Both the flowers and leaves are odorless.  Young plants produce 100,000 – 300,000 tiny seeds per year while older plants can produce 2.5 million.  Seeds are viable for seven years.  Plants often grow in intertwined clumps and the below-ground root mass of each plant can extend several feet.

        Purple loosestrife invades wetland areas, marshes, lakes, ditches, potholes, stream and river banks, crowding out all other vegetation.  By eliminating native plants, it removes sources of food and shelter for wetland animals, insects and waterfowl.  Some species may disappear entirely.  Hunting, fishing, trapping, bird watching and boat travel become impossible.  A purple loosestrife-filled wetland does not filter and store water like a wetland that consists of a variety of native plants.

        Purple loosestrife is classified as RESTRICTED in Wisconsin by Rule NR40.  This means you are not allowed to buy, sell, transport, or introduce it.  You are allowed to possess purple loosestrife, that is, allow it to continue to grow on your property, but you are strongly encouraged to eradicate it.

        New invasions of young loosestrife plants can be pulled or dug from the soil before seeds set.  This is easy in gravelly or loose soil but nearly impossible in heavy clay.  Be sure to get all of the root pieces.  Burn, bury or landfill the plant material; do not compost.  You’ll need to follow up later the same season and in years to come for missed plants.

        The best, most effective way to control large stands of purple loosestrife is biocontrol, the release of tiny, less than 1/8-inch, galerucella beetles.  They eat the plant’s leaves which reduces the height and seed output of the plants. 

        Biocontrol of purple loosestrife beetles began in Wisconsin in 1994.  Brock Woods of the Wisconsin DNR is the father of purple loosestrife biocontrol in our state.  He instituted programs whereby citizens would raise galerucella beetles around the state and then release them in loosestrife-infested areas.  Since the program’s inception, hundreds of citizens have released millions of beetles.  We thank Mr. Woods for his foresight and dedication to purple loosestrife control!

        In 2006, I participated in a project raising and releasing galerucella beetles.  In spring, some ambitious Master Gardeners from Winnebago County went out to a marsh and dug up purple loosestrife roots.  Each project participant was given several roots which were then planted in large pots.  After my pots were planted, I placed them in a water-filled baby pool in my backyard to simulate a wetland.   Several weeks later when the plants had begun to grow and leaf out some, I was given about 100 galerucella beetles.  Each pot was enclosed in netting, trapping the beetles inside.  As the plants grew, the beetles laid eggs.  Over time, the eggs hatched into larvae and the larvae grew into several thousand adult beetles.  In July, my dad and my husband and I loaded the pots, nets and all, into my dad’s motorboat.  We placed the pots, minus nets, in several spots in the marsh along the shoreline of the Fox River where we found loosestrife already growing.  We also placed pots along the Terrell’s Island breakwall which juts out into Lake Butte des Morts. 

        Soon, the beetles began to explore their new neighborhoods and spread to other purple loosestrife plants in the vicinity to feed. 

        Thirteen years later the progeny of those first beetles are successfully keeping the purple loosestrife population under control in the areas where we placed the pots.  Don’t get me wrong – there is still purple loosestrife in the marshes, but it isn’t the dominant plant.  This project was a definite success!

        At this point we can’t hope to eradicate purple loosestrife in Wisconsin.  The goal is to keep it from being the only plant species in the marsh.  And we actually don’t want it all to die out.  If it did, the beetles would also die for lack of food, leaving the marsh ripe for another purple loosestrife invasion, should a seed or root piece survive. 


If your group, workplace or school would like to participate in raising galerucella beetles to control purple loosestrife, there is information here: or email   Don’t try to go it alone!  The DNR and University of Wisconsin Division of Extension will provide valuable help.  A free WDNR permit from the Biocontrol Program is required to cultivate loosestrife to raise control beetles.


The DNR wants to track the extent of purple loosestrife in Wisconsin.  You can help by using one of several ways available to report a purple loosestrife invasion.  Visit  Or call or email Jeanne Scherer at 608-266-0061 or  Other ways to report purple loosestrife or any other invasive species:  For smartphone reporting, download the EDDMAPS app.  For PC use, go to and follow the instructions.

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