|Images from Wikimedia Commons|
The Monarch was one of the species initially classified by Linneaus in 1758's Systema Naturae, and its scientific name comes strait out of mythology. In short, Danaus was a king and had 50 daughters, while his brother, Aegyptus, had 50 sons. Aegyptus wanted the 50 sons to marry the 50 daughters but Danaus refuses until he gets forced into organizing a mass wedding. He then has his daughters kill their husbands, and all but one does. The remaining son gets revenge on Danaus, and he and the daughter become king and queen to a dynasty. See where all this royalty stuff comes from? (Oh, and the species name, plexippus, comes from a name of one of the sons) It has also been speculated that the "Monarch" name is to honor King William III of England (William the Orange in his Dutch Homeland). This is interesting because the butterfly was not called "Monarch" until 1874, while William III ruled 1689-1702, nearly two hundred years earlier.
And last but not least, Monarch Butterflys are poisonous. And where do they get that toxicity from? Their diets of course! They consume milkweed which gives them high concentrations of cardenolide, which is harmful to most predators.