The Sagebrush Checkerspot (Chlosyne acastus) is a medium-sized butterfly belonging to the brush-footed family, well-adapted to arid environments in western North America.

Scientific Taxonomy

• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Insecta
• Order: Lepidoptera
• Family: Nymphalidae
• Subfamily: Nymphalinae
• Genus: Chlosyne
• Species: Chlosyne acastus (W.H. Edwards, 1874)

Several subspecies are recognized, such as C. a. neumoegeni in parts of the southwestern range. The species is sometimes referred to as the Acastus Checkerspot in certain sources.

Description

The Sagebrush Checkerspot has a wingspan of approximately 1.5–2 inches (3.9–5.1 cm), with forewing lengths around 1.8–2.4 cm in some populations.

The upperside features a distinctive checkered pattern of black, orange-brown, and orange (paler in males, often brighter in females). The wings show black lines, smudges, and checks separating bands of pale to yellow-orange; the hindwing base may appear darker (sometimes largely black with limited orange in males). Postmedian bands can show red-orange tones in some individuals.

The underside is more contrasting, with the hindwing displaying bands of chalk-white (or pearly white spots) and brick red, outlined by black veins and edges. This ventral pattern, with more extensive white compared to similar species, aids identification.

It resembles other checkerspots (e.g., Northern Checkerspot or Rockslide Checkerspot) but is distinguished by habitat preference, lighter ventral banding, and specific wing markings.

(Images: Examples of Sagebrush Checkerspot upperside and underside views from various western U.S. locations.)

Behavior

Adults feed primarily on flower nectar from various plants in their arid habitats. Males perch in strategic locations (such as gulches or along washes) and sometimes actively patrol these areas to locate and court females. Flight is typically rapid and direct when disturbed, typical of many checkerspot species.

The flight period varies by region but generally occurs in spring to early summer (e.g., late April to late June in parts of the range like Oregon). Larvae feed on host plants in the Asteraceae family, including species such as green rabbitbrush (Chrysothamnus viscidiflorus), gray rabbitbrush (Ericameria nauseosa), desert yellow fleabane (Erigeron linearis), Mojave aster, and various asters in the genus Dieteria. The species is univoltine (one generation per year) in most areas, with adults timed to coincide with host plant and nectar availability.

Range and Habitat

The Sagebrush Checkerspot occurs across the western United States, from eastern North Dakota westward to eastern Washington, and southward to New Mexico, southern Arizona, and eastern California. It is found in states including Montana, Idaho, Oregon, Wyoming, Nevada, Utah, Colorado, and parts of the Great Basin and Southwest. Populations extend into shrub-steppe regions of southern British Columbia in some accounts, though primarily a U.S. species.

It inhabits dry, arid lowlands, typically below 5,000 feet in many areas (e.g., below 3,000 feet in parts of the Columbia and Snake River basins). Preferred habitats include sagebrush scrub, pinyon-juniper woodlands, dry gulches, washes, canyons, brushy flats, sage deserts, and hilly short-grass prairies. It thrives in shrub-steppe and semi-arid environments dominated by sagebrush and associated plants.

Overall conservation status is secure (G5 globally in many assessments), though local populations may face threats from habitat alteration in arid regions. It is not generally considered rare or imperiled across its broad range.