By Jenny Seifert, UWEX Aquatic Invasive Species Outreach Specialist
Now is the time to be growing purple loosestrife, an invasive plant, in your backyard.
What, you ask? Why would you tell us to intentionally nurture an invasive species?
Good question. Normally, we shouldn’t be planting or otherwise encouraging invasive species in our gardens, ponds or properties.
But purple loosestrife is an oddball case. Tending just a couple of specimens of this otherwise unwanted wetland invasive can be beneficial if done to help their worst enemy, Cella beetles, grow and flourish.
The beetles, formally called Galerucella pusilla and Galerucella calmariensis, have become heroes for wetland lovers, because they are really good at eating purple loosestrife. Their appetites prevent the plants from growing tall and producing seeds, allowing native wetland species to thrive instead.
About two decades ago, the DNR and partners first released the European-native Cella beetles in Wisconsin in an attempt to “stem the purple (loosestrife) tide,” which was consuming so many wetlands that land managers had nearly given up hope that it could be tamed. Now, the beetles are a frontline defense against this wetland-ruining (although, kinda pretty) exotic plant.
Each spring, the beetle army gets a little help from people around Wisconsin, who rear new recruits to be deployed come summer. Each cohort starts small but multiplies quickly – up to 100 times the starting population – before flying off to duty.
You can help raise an army, too! Here’s what the task entails:
- Order a “starter kit,” containing beetles and cage netting, from the Wisconsin DNR for a $20 donation (it’s free to teachers!) by filling out this application. The DNR will mail the netting to you immediately and the beetles in May.
- Once the netting arrives, sew it into “cages,” which you will attach to your purple loosestrife planting pots (don’t worry, instructions will be included) to protect the plants and beetles from other critters that might eat them.
- As soon as the spring thaw hits, dig up a few of the tallest loosestrife plants from your property or, with landowner permission, a nearby infested wetland. Pot and cage them immediately, and place them in your backyard or schoolyard. Here’s how to identify purple loosestrife, if you don’t know what it looks like. (See also the pictures below.)
- By May, your plants should be two or more feet tall, and it will be beetle time. As soon as you get your beetles, place ten of them in each cage with the plants.
- In June or July, you will start noticing new adult beetles in the cages, which means it’s time to move the potted plants to a nearby loosestrife-infested wetland, which may or may not be the same one from which you collected them.
- Remove the cages and release the beetles!
- Report your release to the DNR, including the location, so we can keep track of your much-appreciated efforts.
If you really want to geek out, you can help the DNR monitor your beetles and their progress by photographing your wetland year to year and filling out this form.
This letter has more details about how to get involved in Cella beetle rearing, or you can contact the state’s purple loosestrife guy, Brock Woods, at brock.woods [at] wisconsin.gov.