A monarch butterfly caterpillar, about two to three days old, has eaten a milkweed leaf in Glenn Marangelo’s backyard in Missoula. The Missoula Butterfly House and Insectarium development director said the dots of sticky, milky sap seeping from the damaged area contain toxins, which the larva is resistant to. The monarch butterfly caterpillar exclusively eats the milkweed, using the toxin buildup to its advantage by becoming unappetizing to predators. (Photo by Glenn Marange…
March 1, 2026
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