In the summer of 2021, I found purple loosestrife abundantly growing on my property and along my lakeshore. After actively pulling roots from the shoreline, I knew I needed to find a better way to mitigate it.
Purple loosestrife is native to Europe and Asia and therefore an invasive species to North America. This fast-growing dense plant will quickly out-compete our critical native plants along the shorelines and take over. Purple loosestrife creates unsuitable habitat (food, shelter, nesting) for animals/insects and will harm the delicate balance of the ecosystem if not managed.
Therefore, in 2021 I began my research on how to control purple loosestrife along shorelines. It wasn’t easy for me to find information, but eventually I was introduced to Chris Hamerla. Chris is the Regional Aquatic Invasive Species Coordinator at Golden Sands and works on the Resource Conservation & Development Council, Inc. Chris is familiar with purple loosestrife and has become my coach through the process.
The possible answer...... Galerucella BEETLES!!
I’d like to share my story and the process with you.
April 2022 – FIRST ..... the PLANTS
Chris brought 2 dozen purple loosestrife plants in containers, 2 kiddy pools and some netting to my home.
The plant containers were placed in the kiddy pools and water added to the pools. Nets were placed over the top of the plants to keep out other insects and trap heat, which helps with plant growth. The tops of the plants were snipped to encourage the plant to branch. The more branches the more leaves and surface area for beetles to grow and lay eggs on.
My task was to keep the plants in the water, but not over the top of the containers, which was quite a challenge due to evaporation and cool weather.
May 22, 2022, PROGRESS
My loosestrife plants grew quickly. Some were only 12" high but most were 24"-30" high. Chris started to collect beetles from various sites around Marathon County. Chris wanted my plants to be 24" or higher for the best results.
June 1, 2022
Chris brought beetles to release inside the netting. Now we wait, and let them eat the plants, mate and lay eggs.
June 27, 2022
The weather was hot and humid and the beetles have eaten most of the leaves.
Chris said it was time to release them next to loosestrife infested area. I took the netting off the potted plants and placed them in the wetland as best possible.
I continue to send pictures to Chris in order to learn and keep him in the loop of this project.
July 23, 2022 RESULTS:
SUCCESS ! IT LOOKS LIKE THE BEETLES ARE DOING THEIR JOB. If there is enough loosestrife in the immediate area, Chris encouraged me to raise and release again in 2023. If the loosestrife in that area becomes too low for the beetles (a good thing) they will just fly to another site.
At this point I'd say..... keep adding beetles.
October 10, 2022
Per Chris “While you did release beetles this year, adding more in 2023 and the next couple of years would be best. Plus, there are plenty of other locations on the Chain which could use beetle’s and purple loosestrife control”
Chris mentioned that beetles released in 2022 should make it through the winter and suggest I raise and release again in 2023. I have pots, pools and netting so I’m ready to go. I will stay in touch with Chris through winter/early spring and I'll let him know when I will be digging new roots in order to grow new plants for my pots/pools. Easy enough since they could just be gathered from the area by my house.
I continue on in 2023 with greater understanding of the process and hopes of a greater impact on this invasive plant.
I walked out on ice cover and cut back some of the growth and burned plants
Chris let me know that any beetles that overwinter will be in leaf litter along the shoreline.
SPRING 2023 - WE CONTINUE ON:
April 2023 PRUNING
Earlier, I had collected 16 host plants from my property which were now anywhere from 2" - 8" tall. Chris mentioned that “once my plants get to be 12" I should snip off the terminal bud (top of the plant) to again encourage branching”. He mentioned how this bud would be recognizable because it has tightly packed leaves at the top.
I needed my potted plants to be at least 20" tall with good branching when we add the beetles.
Once my plants reach this height, I will add beetles that Chris had collected for me.
It’s worth noting that 2023 was a difficult year for Chris to collect beetles because of weather conditions. Per Chris: “I will be watching my beetle collection sites during the next couple of weeks. As soon as I see beetles, I'll let you know I’ve started the collection process and will get them to you.”
He was eventually able to bring me enough to add to my 16 netted and potted host plants.
May was cool with not much rain which made it less than ideal conditions for the plants to grow and beetles to eat and propagate. I was constantly monitoring the plants.
Finally…. in June, there appeared to be evidence that some of my potted plants had active beetles. For best results, Chris mentioned simply placing my “host” potted plants next to the infested loosestrife wetlands. I would release my beetles in stages as host plants seemed to mature with active beetles at different rates.
Chris informed me that in just two days, four of his pots went from "Ok looking" to beetles “NEED to be released now". It was the beetle larva that have killed the plants, not the beetle itself. He advised me to check daily, if I see the same, I was to take the dying plant with larva and place them with wild purple Loosestrife, intertwining any dying stems with healthy wild plants. This is only if larva are killing my plants. If my plants are still healthy enough and not wilting, I should wait and hopefully the beetles will hatch so I can release those.
July 3, 2023
Beetles were released onto wetland purple loosestrife. I am documenting closely “where, when and how much” I release in order for Christ to keep records of the area.
Although there was some impact in 2023, there was more noticeable beetle impact in 2022. We believe this may be due to the difficulty in collecting beetles in April, the cold weather in May and the lack of rain in June.
July 25, 2023
I needed to ask Chris if it would be beneficial to cut the flowers off the wetlands plants or would there be negligible effects as I would be interested in doing this in 2024 vs beetles. I’m simply not sure if this sight would be beneficial for raising beetles.
Per Chris: Cut the flowers or just remove the entire plants from the pots and knock off as much soil as you can. Discard of the plants by: 1. allow it to dry out a bit and burn. 2. place them into sealed garbage bags and leave in the sun for a while, then landfill them (still contained in the sealed bag). There is some benefit to cutting the flowers and disposing of them. That will remove the seed supply for future plants and does stress the existing plants. The immediate, noticeable effects of doing this will be minimal but if you continue to do it year after year you should notice the plants becoming shorter. This allows more native species to compete for space. Time will tell".
WHATS NEXT ? 2023 and BEYOND
I will continue to monitor the wetlands to see what effects the beetles are having. So far there has been less in 2023 than in 2022, however nature is always in a state of flux and can be challenging. It is my plan to continue documenting the area until the fall.
Chris and Golden Sands Resource Conservation & Development Council are in the process of revisiting the process and possibly raising beetles in certain key areas by creating contained incubation grounds.
I am hoping that one of these beetle raising areas could be developed here.
Stay tuned ….. more to come. If you want to help or be involved, please feel free to reach out to me at the WCOLA or Chris Hamerla
IMPORTANT NOTE regarding Galerucella beetles:
Although galerucella beetles are not native to NA, they have been studied and tested as a biological control for purple loosestrife since 1986.
To read more about these beetles and their impact on PLS and the environment, please read "Success Takes Time" by Stacy Endriss, Vicoria Nuzzo and Bernd Bossey. Also see "Purple Loosestrife Biocontrol History, Answers to Common Questions" by Golden Sands, RCD council.
Blog post by:
Waupaca Chain O'Lakes Association
Stewardship and Resources Committee member
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Waupaca Chain O'Lakes Association
Stewardship and Resources Committee
Chair(s): Julie Mazzoleni, Fawn Johnson