Summer of the passion butterfly
Gulf fritillaries invaded Oklahoma this year. How much do you know about them?
It’s October 24th, and midday temperatures are still peaking at nearly 80 degrees in Bixby, Oklahoma. The lower half of the view out my back porch door is still awash in bright yellow blooms with swirling orange specks.
I let the accidental golden crownbeard patch expand to ridiculous proportions this summer. A slight miscommunication with a landscaper wiped out—and I mean chopped down to bare dirt—the rest of our wildflower plots early in June. Most of it came back in spurge—think small wilted invasive poinsettias—and morning glory vines. Blech.
However, the purple passion vine and the golden crownbeard also responded. Both are resilient plants. I just let ’em run wild to see where it all would end up. About 900 square feet of our 3600 square-foot backyard is covered in golden crownbeard and passion vines at season’s end. The impenetrable mound is about 5 to 6 feet high. It’s a jungle out there.
And it has been heaven for Gulf fritillaries, which arrived in banner numbers across most of the state this summer.
Regional butterfly interest groups loaded social media with photos of the bright orange, flashy critters this summer. The first showed up in the daisy patch here around July 20th. I still see at least two daily in the backyard three months later. Late August and early September had peak activity. One morning, I counted eleven adults flitting around, at least 46 caterpillars on the passion vines, and mating and egg-laying were still in full swing.
I’ve had passion vines and other flowers in my yard for at least eight years, and I’ve always seen a frit or three. I’ve never seen anything like this, every day, all summer.
A bright female flitted into and out of tangles around the base of a bird-feeder post earlier this week. Sure enough, she was laying eggs near that healthy patch of passion vine.
I told her, “I’m afraid you’re a little late there, babe.”
Longwings vs. Frits
John Fisher, my go-to local lepidopterist with a lifetime of observations, agreed that 2024 was the summer of the fritillaries.
Early summer saw a boosted Diana rush that drew excitement for a species listed as uncommon in this state. Regal fritillaries made news in early August, with the U.S. Fish and Wildlife Service proposing an Endangered Species Act listing.
Meanwhile, the Gulf frits exploded everywhere.
“Except they aren’t really fritillaries,” Fisher said.
It’s true; they are not “true fritillaries,” a moniker folks like Fisher reserve for the so-called greater fritillaries, which include fourteen species of the tribe Fritillaria and genera Speyeria. In Oklahoma, that consists of the Diana, Regal, Great-Spangled, and Edwards. Their host plants are violets. They mate in late summer and lay eggs in fall. Their caterpillars don’t eat and overwinter in the duff and surface soils near violets.
The saying goes, “Without violets, fritillaries do not exist.”
They are distant cousins of Gulf fritillaries in that they are part of the family of brush-footed butterflies, Nymphalidae. All have short, clawless, brush-like front legs and stand mostly on four legs. But it’s a big family, which includes about 6,000 other species.
They are of the same subfamily, Heliconiinae.
According to the fine folks at BugGuide.net, based at Iowa State University, the subfamily of Heliconians was only expanded to include several tribes, including Fritillaria, in recent decades.
“Heliconiinae, the Heliconians and Fritillaries” is the standard reference to the subfamily.
It gets even more confusing as you delve into the different genera and dozens of species.
The basics are that Gulf fritillaries share some similarities in looks with true frits, most of which relate to coloration, with shades of orange or brown with black patterns and have at least some hints of silvery-white patches on their underwings. Oklahoma’s ecological requirements for these two genera overlap. Because of its geography, this state hosts an incredible diversity of butterflies from the Kiamichis to the Panhandle. These are just two of more than 170 documented here.
Fritillaries find timber edges, brushy meadows, bogs, and prairies with plentiful violets. The Gulf fritillaries find more moderate temperatures and plenty of passion vines for reproduction.
But that’s where the similarities end. Gulf fritillaries are tropical longwings that must fly south to overwinter. Some, like the one laying eggs in my yard this week, seem to push it to the bitter end. Most reports note that 21 degrees is the minimum survivable temperature for them—and I’d have to assume that an egg, adult, pupa, or larva would only survive a temporary dip below freezing.
Unlike fritillaries, they survive on passion vines, not violets. They migrate north in spring to produce multiple generations and return south to overwinter as adults across the southern U.S., south to Central America, and the West Indies.
Bringing passion butterflies to your backyard
Passion butterfly is another common name for the gulf fritillary, and that’s the better fit. Somehow, it sounds even more tropical.
Eyeball BONAP’s North American Plant Atlas for distribution of Passiflora (passion vines) and where sightings of Passion butterfly (Dione Vanillae) are most prevalent across the U.S. on the iNaturalist distribution map, and it makes sense to name them for passionflowers.
Their caterpillars devour the leaves and stems. I watched one seemingly drink up the sap at a chewed-off stem as droplets formed around its mouth. The fluid in the vines contains a sugar called cyanogenic glycosides, which turn into cyanide when eaten. This makes the caterpillars distasteful and slightly toxic, a condition that lasts in the adults as well. Their bright orange coloration is a warning to would-be predators.
Fisher said anyone’s guess explains the prevalence of passion butterflies this year. Weather and favorable conditions for germinating passion vines are likely at its root.
The population is healthy and not closely monitored. People report migrations across the South, but Fisher said passion butterflies are not tracked or tagged like monarchs. No one knows whether butterflies arrive in Oklahoma from the Texas Coast, Alabama, Florida, or various places.
All I know is they’re pretty cool.
To join in the enjoyment, you only need some passion vines and other nectar sources in your backyard. The vines love a trellis, fence, or bushes and do pretty well just running along the ground. I put a tall plant stake in the ground to mark a mystery weed I wanted to identify after it grew a little more, and the next thing I knew, a vine was up that stake, reached some low tree limbs, and climbed up into our oak tree. They can stretch 25 feet.
Nurseries specializing in native plants are places to look for seeds or potted plants in season. Okies for Monarchs maintains a great list of Oklahoma sources.
Seeds, I’ve been told, are notoriously tricky to germinate. Then again, a few successful sprouts will multiply year over year, so it might be worth a shot. Four or five will give your yard a healthy start and fill a trellis quickly.
The first few vines in my yard came from a friend who had a sprawling garden. We dug a few volunteer sprouts one spring day, and I transplanted them. Some healthy watering helped them take root, and that was it. They did OK that first year. Since then, they seem to pop up everywhere, even in the middle of the yard.
Low maintenance is an understatement.
This summer, I learned that golden crownbeard, also called cowpen daisy or butter daisy, can be a staple for these tropical visitors, especially during an extremely dry September.
Again, a low-maintenance plant that likes to spread.
Various sources list an incredible variety of native plant nectar sources preferred by passion butterflies, from red clover and thistle to phlox, lantana, ironweed—and, of course, passion vine.
Your video is enchanting and well narrated. As soon as daylight breaks, I will inspect the remaining fall flowers in my yard for this butterfly.
Charlie Transue
Tulsa
Good Job, Kelly