Hike into Bend’s high alpine right now and you’ll notice something before you even hit treeline—flashes of orange and black zigzagging across the trail, landing on sun-warmed rocks, and weaving between wildflowers like they own the place.

It’s easy to assume you’ve stumbled into the monarch migration. We get it—same bold orange-and-black pattern, same grand entrance. But these aren’t monarchs. They’re California tortoiseshell butterflies, and in years like this, they show up in numbers you can’t ignore.

According to the Deschutes Land Trust, it has a lot to do with the availability of snowbrush (a type of Ceanothus) for caterpillars to feed on and the timing of a second brood in summer. We’ll just say it’s one of those years where they’re everywhere. Our team has spotted them on the summit of South Sister, in the meadows above Green Lakes, and along Tam McArthur Rim—sometimes in swarms big enough to make you stop mid-hike and just watch.

If you’re heading for the high country in search of this summer’s butterfly boom, be aware that many popular trailheads require a Northwest Forest Pass, and some areas in the Central Cascades also need a wilderness permit during the busy season. Learn more about permits in the Central Cascades before you go.

At a glance, it’s easy to confuse California tortoiseshells with monarchs. But their stories are different. Monarchs migrate thousands of miles each year to and from Mexico. California tortoiseshells are homebodies of the West’s mountain ranges, spending summers high up—sometimes in massive groups—and moving downslope in the fall.

So if you spot them on your next hike, you’ll know who they are. Enjoy the sight, maybe let one photobomb your trail selfie, and pass the ID along to the next hiker who asks.