Monarch butterflies and mimicry

Monarch butterfly
(Danaus plexippus)

The monarch butterfly is a common resident of north and south america.

Caterpillars of this species feed on the milkweed plants, incorporating cardenolides (also known as cardiac glycosides) from the plant into their own chemical make up. As adults, these beautifully colored insects retain the protection afforded to them by the chemical, and it proves quite effective against any potential predators.

Unable to survive the harsh winters, these small butterflies undertake a vast migration, either to Mexico or the coast of California. During migration, they act as birds do, stopping for the night, forming roosts of up to one thousand individuals, and traveling in groups.

for more information, check out:
Oberhauser KS, Solensky MJ (2007) Monarch Butterfly Ecology. ECOLOGY.INFO 28

Of course, no discussion on the Monarch would be complete without mention of mimicry. The Viceroy (Limenitis archippus) and the Monarch, are classic textbook examples of mimicry. The Viceroy very closely resembles the Monarch in coloration and markation. Unlike the species it mimics, however, the Viceroy does not assimilate any chemicals into its tissues – meaning it is a potentially tasty snack for any predator who happens along. However, not too many predators are keen on eating a Viceroy. This is because of the strong resemblance to the less-than-palatable Monarchs. When a predator eats one of the noxious species, its efforts are rewarded by vomiting, upset stomach, and otherwise unpleasant events. Its no wonder when the Viceroy comes along, taking full advantage of the protection afforded by its gaudy coloration, potential predators quickly become unlikely.