Where the trees give out and the slope turns into loose rock, a small black butterfly with pale orange and cream bands is sometimes sitting in the hollows between the boulders. That is the rockslide checkerspot, Chlosyne whitneyi. The Colorado Front Range butterfly guide calls it the only checkerspot of its genus normally found above timberline, and Butterflies and Moths of North America (BAMONA) labels its range simply “rare.”
Identification: black, orange and cream bands
BAMONA describes the upperside as slightly glossy black with pale orange to creamy white bands. The female may be much darker. On the underside, the hindwing carries a light orange marginal band, then alternating orange and creamy white bands over the rest of the wing. The Colorado guide describes the same pattern from the field side: pale brown-orange with black markings above, variable, and a creamy white hindwing below. Wingspan runs 1 1/4 to 1 5/8 inches (3.2 to 4.1 cm) in BAMONA; Wikipedia gives 32 to 41 mm.
Habitat does half the identification work. A banded checkerspot on a high rockslide in July is a better candidate than a similar-looking one in a meadow, since the rest of the genus lives lower. The place and the date matter, so write down the elevation if you photograph one.
Range and habitat
The species is found in western North America from British Columbia and Alberta south, in the mountains, to California and Colorado. The Butterflies of America catalog records its type locality in California, which fits the alternative name Sierra Nevada checkerspot. BAMONA gives the habitat as rocky slopes, benches and rockslides at or above treeline. Wikipedia lists alpine rockslides and scree slopes.
Two subspecies are recognized in Wikipedia: the nominate whitneyi and damoetas. The page does not map where one stops and the other starts, and neither does this one.
Flight season
There is one flight a year. BAMONA says July to August, and Wikipedia says the same. The Colorado Front Range guide widens it to late June through August, which is reasonable for a species that waits for snow to leave high ground.
Life history
Males patrol and sometimes perch in the hollows of rockslides, waiting for females. Eggs are laid in batches on the underside of host-plant leaves and sometimes on flower buds. The caterpillars eat leaves and flowers and feed together in groups, and BAMONA’s host line reads: alpine plants of the sunflower family including Erigeron and Solidago species. Adults take flower nectar.
The slow part comes next. Third and fourth-stage caterpillars hibernate under rocks, and some stay in diapause for two years or more to survive bad weather. The Colorado guide states that the life cycle may take two or more years to reach the adult stage. A species that grows up this slowly cannot recover quickly from a bad run of seasons, which is one reason the word rare appears in its entry.
Status
BAMONA’s conservation line says “not usually required,” and its management line reports no needs. Wikipedia cites NatureServe for the habitat statement. This page found no protected-status listing in the sources it reviewed, so none is claimed.
What a gardener can and cannot do
The honest answer for a yard is that nothing a gardener plants will bring this butterfly in. It lives above treeline, on scree, and no source describes any garden planting that draws it. Goldenrod and fleabane are the caterpillar plants, and both are ordinary garden genera, but the species is tied to the alpine places where those plants grow wild and where the caterpillars can shelter under rocks through a multi-year life cycle.
What a gardener inside its range can do is visit. Mountain hikes in July and August, up to treeline and the rockslides above it, are where the records come from. The butterfly garden guide covers the plants that help butterflies at lower elevations, and the Persius duskywing is another western species whose caterpillars use plants that gardeners can actually grow.
Hibernating under a rock for two winters in a row is an odd way to run a life, and it is the detail most worth remembering about this butterfly.
Common questions
What is the rockslide checkerspot?
It is Chlosyne whitneyi, a small brush-footed butterfly (family Nymphalidae) of western North America. It is also called the Sierra Nevada checkerspot, a name tied to the Californian place where it was first described. Butterflies and Moths of North America lists it as rare, living on rocky slopes, benches and rockslides at or above treeline.
How do you identify a rockslide checkerspot?
The upperside is slightly glossy black with pale orange to creamy white bands, and the female may be much darker. The underside of the hindwing has a light orange marginal band and then alternating orange and creamy white bands over the rest of the wing. The wingspan is 1 1/4 to 1 5/8 inches (3.2 to 4.1 cm).
When does it fly?
It has one flight a year. BAMONA gives July and August, Wikipedia agrees on one generation from July to August, and the Colorado Front Range guide says late June to August. The differences are small and likely reflect elevation and snowmelt, though none of the sources says so outright.
What do the caterpillars eat?
Alpine plants of the sunflower family, including Erigeron (fleabanes) and Solidago (goldenrods) species. The caterpillars eat leaves and flowers and feed together in groups. Eggs are laid in batches on the underside of host leaves and sometimes on flower buds.
Why do the caterpillars take so long to grow up?
Third and fourth-stage caterpillars hibernate under rocks, and some diapause for two years or more to survive bad weather, according to BAMONA. The Colorado Front Range guide says the life cycle may take two or more years to reach the adult stage, which fits a species living above treeline.
Can I attract it to a garden?
Not in any way the sources support. It lives on rockslides at or above treeline, and none of them describes a garden planting that draws it. Goldenrod and fleabane are listed caterpillar plants, but the butterfly belongs to the alpine habitat where they grow wild.