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Invasive plant spreads in West Michigan, hurts monarch butterfly

You would be hard-pressed to find someone who doesn’t think of Monarch butterflies at the mention of milkweed. Funny name too when you think about it. In West Michigan, Monarch butterflies are facing a deadly threat from a growing invasive species: black swallow-wort. Last night, I met with Jessie Schulte, a land management expert from Blandford Nature Center and Master Naturalist Ginny Wanty from the West Michigan Cluster of The Stewardship Network to learn more.

Black swallow-wort flowering.
Black swallow-wort flowering.

We need to talk a little biology, so bear with me. Monarch butterflies have various sensors on their body known as chemoreceptors. A chemoreceptor translates chemical stimuli from outside the body into action potential in the nervous system. In English, they allow them to taste and smell. Now, we think of taste and smell at a high level in terms of our likes, dislikes, food, perfume, and certain streets in Chicago.

From a scientific perspective, taste and smell are signals sent to our brain telling us that a certain chemoreceptor has noticed a particular chemical. If this sounds confusing, that’s okay. You already know some of your chemoreceptors by another name: tastebuds.

For Monarchs, these sensors are finely tuned to recognize a chemical released by milkweed. The fluttering insects are drawn to the plant like a bull to the color red. Monarch larvae eats milkweed exclusively, so the plant is important for their survival.

In this analogy, if the milkweed plant is the color red, the black swallow-wort is the matador waiting to pull the cape away. It tricks the chemoreceptors. If given a choice between the two, a Monarch will land and deposit their eggs on the swallow-wort, Wanty explained. Why is this a problem? Black swallow-wort is toxic to Monarch larvae. By the way, it is also toxic for cats, dogs, and livestock.

Black swallow-wort with open seed pod.
Black swallow-wort with open seed pod.

The Kudzu of the North

“I like to call it the Kudzu of the North,” Jessie quipped. Waxy pointed leaves grow opposite from narrow, elongated seed pods. The vine grows thick like Kudzu, wrapping around itself back and again. Black swallow-wort is native to Eurasia.

A thick infestation can produce over 2,000 seeds per square meter of plant growth. And not only do the seeds disperse quite effectively through the air, but the plant also grows via underground stems called rhizomes.

Oh, and the flowers are self-pollenating. As you can imagine, it overwhelms and crowds out native species quite quickly and effectively.

What do I do if I find black swallow-wort?

Report it. Where? Through the Midwest Invasive Species Information Network (MISIN). It is best to leave treatment work to trained professionals. Well-meaning attempts to deal with invasive species without proper training can be a major source of their spread when done incorrectly. Early detection and prevention is key. You can help make a difference.

It spreads. Fast and far. You may not have pets, but your friends, family, and neighbors do. They need your help to prevent black swallow-wort from becoming prevalent and hurting not only the environment and economy, but pets and other animals.




  1. Sue Greenhoe Sue Greenhoe September 1, 2016

    I would like to make handmade paper out of invasive species Can some one give me info on getting some of these for paper making?

    • Maurie Houseman Maurie Houseman September 18, 2016

      I recently came across an invasive plant called Velvet Leaf that has a long stem and had been used in days gone by for fiber to make cables for sailing ships. It’ a native of China. I’m not sure if it would be good for paper, or where to get an ample supply. Just a thought.

  2. Billie Jean Stout Billie Jean Stout September 2, 2016

    We live on a small lake in Kent Co, Our swampy edge has been invaded by Loosestife, and what I think if called fountaingrass, the cat tails seem to be loosing space to the fountain.grass.. I also found something that I am concerned with that looks like Queen Anns lace but is not the same.. Our lake has been so beautiful and like a retreat for so long.. I hate to think of losing that quality.. I was told that it was the clearest lake around.. In the years I have lived here I have seen many changes… The lake is spring fed and much of the surrounding land is very low. Many old cottages that are not on a sewer line.They were once only used during the summer, Many are not year round.. We have had pollution of some of the water that feeds into the lake… I wish I knew how to stop progress and preserve what was once a treasure..

    • Adrian de Novato Adrian de Novato Post author | September 2, 2016

      I’m very sorry to hear about your purple loosestrife infestation! Such a beautiful, yet aggressive invasive.

      Poison hemlock looks similar to Queen Anne’s Lace but with a hairless stem with purple blotches. Does that sound familiar?

    • Maurie Houseman Maurie Houseman September 18, 2016

      The plant that looks like Queen Anne’s Lace could well be Poison Hemlock, which is VERY POISONOUS.
      It can grow larger than Queen Anne’s Lace, has purple on the non-hairy stem, whereas Queen Anne’s Lace has no purple on hairy stems. Look it up on the internet. Call me or email if you like, for any questions about invasive plants. Maurie Houseman, Izaak Walton League of America, (Conservationists), 616-560-2895

      Also, the Purple Loosestrife can be controlled by a beetle, that keeps it in check in it’s native environment, (called biological control), and has been introduced in this country with marked success. For more information on that call Bob Stegmier at 866-4769

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