Danaus plexippus
Insect · Butterfly · MigratoryA monarch on the wing reads almost lazy: a few shallow flaps, then a long flat-winged glide that carries it across a meadow on the warm air. Move a hand near a feeding adult and it lifts off in no hurry, orange wings catching the light like stained glass before it settles on the next bloom.
That ease hides one of the longest insect migrations on Earth. Each fall, monarchs east of the Rockies funnel thousands of miles south to a handful of mountain groves in central Mexico, clustering so thickly on the oyamel firs that the branches bend under them. The butterflies nectaring in your yard this June are the great-grandchildren of last autumn's travelers, working north generation by generation as the milkweed greens up behind them.
Everything about the monarch is a warning. The caterpillar feeds only on milkweed and banks the plant's bitter toxins in its own body, and the adult keeps them. The bold orange and black is a billboard to any bird that has tasted one before: leave this one alone.
Deep orange wings crossed by thick black veins, edged with a black border dotted with white spots. The pattern is bold and even on both upper and lower surfaces.
Males carry a single black scent spot on a vein of each hindwing. Females have no spot and noticeably thicker black veins.
The smaller viceroy mimics the monarch almost exactly, but has an extra black line arcing across its hindwing. The monarch's hindwing has no such line.
Watch how it moves: slow, sailing glides on flat wings between flaps, not the quick, fussy flutter of most butterflies. The glide is often the first thing you notice.
In June, monarchs are spreading north across the United States and southern Canada, laying eggs wherever milkweed has come up. Look for them in any sunny open space with flowers: prairie remnants, roadside ditches, old fields, and pollinator gardens. Females flutter low and deliberate, dropping onto milkweed leaves to lay single pale eggs on the undersides. Numbers have fallen far enough that the IUCN now lists the migratory monarch as Vulnerable, and US wildlife officials have proposed protecting it as Threatened.
It takes three to four short-lived summer generations to push the population north each year. Then one long-lived "super generation" hatches in late summer and flies the entire way back to the mountains of central Mexico, navigating by a built-in sun compass, a journey none of them has ever made before.
Asclepias syriaca
Plant · Wildflower · Monarch HostArchilochus colubris
Bird · Hummingbird · MigratoryCercis canadensis
Plant · Tree · Native UnderstoryXylocopa virginica
Insect · Bee · Wood-NestingSetophaga petechia
Bird · Songbird · Migratory