Wildflower Stories: Milkweed, Monarchs and Monsanto

ATwildflowers_milkweedlMonarch butterfly populations have declined an estimated 90% over the past 20 years. [1] What’s going on?! The answer involves genetic engineering, protozoans and herbicide.

Milkweed (Asclepias syriaca), a member of the Dogbane family of plants, is closely associated with Monarch butterflies. Monarch caterpillars feed on milkweed and assimilate the plant’s chemical defenses, providing the Monarchs protection over the rest of their lives.

Milkweed grows in disturbed soils, like those used in agriculture. The plant is often found between rows of corn or soybeans. However, genetic modification of corn and soybean allows herbicides (such as Monsanto’s RoundUp) to be more efficient at killing other plants, like milkweed. Fewer milkweeds, fewer Monarchs.

So good-hearted people came to the rescue, planting Milkweed in their yards in an effort to help the butterflies. Unfortunately, many people planted the wrong species of Milkweed. Here in the U.S., native Milkweed dies back each year. This dieback limits the population of a Monarch parasite called OE (Ophryocystis electroscirrha). [2] However, the species of Milkweed people planted is evergreen, so the parasites keep proliferating and Monarchs get so sick they don’t survive their migration to Mexico and back.

If you’d like to find the right Milkweed for your neck of the woods, here’s a handy tool from Xerces.

  1. http://news.nationalgeographic.com/news/2014/10/141010-monarch-butterfly-migration-threatened-plan/
  2. http://monarchparasites.uga.edu/whatisOE/

10 thoughts on “Wildflower Stories: Milkweed, Monarchs and Monsanto

  1. While I have heard about the decline in Monarch population due to the decline (or decimation) of Milkweed, you blog brings to light the importance of re-planting the RIGHT variety of milkweed! Thank you for this. My heart sings every time I see native Milkweed, as I Love Monarchs and morn for their struggle!

    • Thanks for your comment, Laura. Monsanto is quite a challenge – I don’t know anyone who’s a fan, yet without GMO crops and chemicals, we certainly would not have as many people survive. Just one of those horrible consequences of overpopulation I suppose.
      All we can do is try to help as much as possible – plant milkweed!

  2. Wildflower Stories: Milkweed, Monarchs and Monsanto – RedNewtGallery | WORLD ORGANIC NEWS

  3. Losing our Plants – RedNewtGallery

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