Originally published in the July 2023 issue of the Wildflower News
The dogbane beetle (Chrysochus auratus) has evolved an adaptation whereby the dogbane’s toxic glycosides (cardenolides) don’t bother it and, reversing the tables, it can use them as a defense against its own predators. (It might be worth looking for these shiny, “metallic” beetles this season!)
The caterpillars of the Monarch butterfly (Danaus plexippus) are known to be able to sequester the cardiac glycosides in their bodies without harm to themselves, but which cause vomiting in birds that try to eat them. This defense mechanism persists in the adult butterfly, whose brilliant colours serve as a warning of its toxicity to would-be predators.
Canada swallowtail butterflies are common locally in our natural areas, usually appearing in June. This photo of the larva was taken in the planted flower bed at Bunchberry Meadows; the adult was captured on low milkweed at Fort Saskatchewan Prairie.
