Chances are if you can identify one butterfly, it's going to be this guy, the monarch, scientifically known as Danaus plexippus. They're plentiful, and they're's easy to spot, with their bright orange wings and distinctive black veins.
And chances are if you know anything about the monarch, it's the amazing migration it makes every year to the conifer forests in the highlands of central Mexico. Amazing really understates what these bugs do. But there is a bit of mystery to the monarch, particularly in Florida. We're not completely sure what they do here, particularly in South Florida, where food is plentiful and temperatures are always mild. Some live here year round; others might migrate, but if so where do they go? And as famiiar as monarchs are to us, they can be a little tricky to identify.
Some monarch basics: They're found over much of eastern and central United States, including all of Florida, and southern Canada. There's also a Pacific Coast population. Monarch have been found in Australia and Great Britain as well as the Azores and Canary Islands. They're medium to large as butterflies go, with a wingspan ranging between 3.25 inches to nearly five. Monarchs are bright orange above, with dark veins and white spots along the edges of the wing. The key identifying feature are the wide borders that separate the forewings and hindwings.
Adult monarchs vary their diet depending on the time of year and what's available, which makes them valuable as pollinators. When milkweeds are in bloom — which in South Florida means all year — they become the nectar source of choice. Monarch caterpillars, however, are notoriously picky eaters and with a reason. Monarch females lay eggs singly on the leaves of milkweeds only, which the caterpillars will devour, acquiring chemicals called cardiac glycosides, which get stored in their bodies as they mature into adulthood.
Those cardiac glycosides are the main form of defense for the monarch and two other members of Danaus genus, the queen and the soldier, which also dine on milkweeds as caterpillars. All three share the orange-and-black color scheme. The glycosides make the butterflies poisonous to predators, particularly birds; eating one probably won't kill a bird but it will make him sick enough to never nibble on anything orange and black again. Because the monarch, queen and solider look alike, they contribute to a common defense.
Now, there is a ringer, the viceroy, which is not a member of Danaus but so closely resembles the monarch it could almost fool one into believing that it's kin. The viceroy has those same heavy black margins separating the fore- and hindwings that mark the monarch. The viceroy has one feature that the monarch lacks, and that is an arcing line across the hindwings that makes a crude semicircle. See that and you're looking at a viceroy; if not, then it's a monarch.
Monarchs are known for their long migrations, from the northern U.S. and southern Canada to conifer forests in California and central Mexico, where they gather by the millions to wait out winter. The trip takes as many as four generations of monarchs to make the full cycle. The generation that makes the trip in the fall will live as long as nine months, long enough to hang out through winter and reproduce in the spring. Succeeding generations will live three to five weeks, spending their energy on reproducing.