Plant Threatens Michigan Monarchs

Apr 20, 2017

Pale swallow-wort found near Saginaw
Credit Saginaw Bay CISMA

Since 2012 a poisonous plant has affected how monarch butterflies in Michigan develop. Swallow-wort was not seen as a problem when it was first brought to the United States during the 19th century. But now the decorative plant in gardens is a threat to monarchs.

Eleanor Serocki is the Coordinator for the SWxSW Corner Corner Collaborative Invasive Species Management Area, or CISMA, covering Van Buren, Berrien and Cass counties. It helps communities manage invasive species that cause problems in the region.

Serocki says all three counties have problems with swallow-wort. She says the plant tricks monarch females into laying their eggs in the wrong place.

“They have milkweed-like seed pods and those seed pods can be used as a visual cue by the butterflies for where to lay their eggs. The butterflies will lay their eggs on the vine but the vines aren’t edible for the caterpillars, so the caterpillars can’t reach maturity.”

Monarch caterpillars can only eat milkweed.

Serocki says there’s a good way to get rid of invasive plants like swallow-wort.

“You can dig or pull the plant. But the trick is that you can’t break off the stem from the root. You have to get the entire root-ball because if you break it off it can reproduce and sprout back up very densely and very quickly.”

Serocki and CISMA hope to teach people how to get rid of the plant to save more monarch butterflies.

For more information, call (269) 657-4030.

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