Milkweed Munching Monarchs

Although scientists have long known that the toxic sap that flows through milkweed veins, called cardenolides, can make a bird very sick if it attempts to eat a Monarch caterpillar, it was unclear whether the butterfly’s acquired adaption to the toxicity was a side effect that allowed the caterpillar to eat the milkweed or had developed separately as a defensive mechanism against predators. A Cornell University study recently published in Proceedings B of The Royal Society Publishing reveals that they have indeed evolved to weaponize milkweed toxins! Thank you so much to Maggie Rosa for sharing “The Scientist” article and you can read more about it here. 

“Monarch butterfly caterpillars have evolved the ability to store toxins known as cardenolides, obtained from their milkweed diet, specifically to make themselves poisonous to birds, as has at least one other species of milkweed-munching caterpillar, according to a study published Wednesday (November 4) in Proceedings of the Royal Society B.

“This finding is fascinating and novel,” Stephen Malcolm, a professor at Western Michigan University who studies cardenolides but was not involved in the new research, wrote in an email to The Scientist. “It is exciting to have evidence for the importance of top-down influences from predators.” Continue Reading

Please join me Thursday evening, November 12th, at 7pm at the Sawyer Free Library for my illustrated talk, Beauty on the Wing ~ Life Story of the Monarch Butterfly. Looking forward to seeing you there!

Meadow Anderson and Milkweed Caterpillar