Chlosyne leanira elegans

Oso Flaco Patch Butterfly

Family: Nymphalidae · Class: Insecta · Order: Lepidoptera

Conservation status: G4G5T1T2 S1S2

The Oso Flaco Patch Butterfly (Chlosyne leanira elegans) is a subspecies of the Leanira Checkerspot, distinguished by its distinctive orange and black checkered wing pattern with white spotting. Adults have a wingspan of approximately 32-38 mm (1.3-1.5 inches). The dorsal wing surfaces display bright orange patches separated by black lines forming a checkerboard pattern, while the ventral surfaces are lighter with more prominent white markings. Males tend to be slightly smaller and more vibrant in coloration than females. This subspecies is endemic to a very restricted range along the central California coast, specifically in the Oso Flaco Lake area of San Luis Obispo County. The population is centered around the Oceano Dunes State Vehicular Recreation Area and adjacent lands near Pismo Beach. Historical records indicate the subspecies once occurred more broadly in coastal dune systems, but current distribution is limited to a few square kilometers of suitable habitat. Oso Flaco Patch Butterflies inhabit coastal dune scrub and adjacent freshwater marsh edges. The species requires areas with native vegetation communities that include both larval host plants and adult nectar sources. These habitats are characterized by sandy soils, moderate salinity influence from ocean proximity, and specific plant associations adapted to coastal conditions. The butterflies typically occur at elevations from sea level to approximately 100 meters (330 feet). Adults are active from March through October, with peak flight periods occurring in spring and early fall. Males establish territories and engage in patrolling behavior to locate females. Females deposit eggs in clusters on host plant leaves, and larvae develop through five instars before pupating. The species appears to have multiple broods per year when conditions are favorable. Adults feed on nectar from various native flowering plants, while larvae are specialized feeders on specific host plants in the coastal dune community. The Oso Flaco Patch Butterfly has a Global/State Rank of G4G5T1T2 S1S2, indicating the subspecies is critically imperiled in California despite the species as a whole being relatively secure globally. The extremely limited range makes this subspecies vulnerable to habitat loss and degradation. Primary threats include coastal development, recreational vehicle use in dune areas, invasion by non-native plants, and habitat fragmentation. Climate change poses additional risks through altered precipitation patterns and increased storm intensity affecting coastal dune systems. The small population size increases vulnerability to stochastic events and genetic bottlenecks. Conservation efforts focus on habitat protection and restoration within the Oceano Dunes complex, though the species lacks formal state or federal listing status. Monitoring programs track population trends and habitat conditions to inform management decisions for this rare coastal endemic.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.