Neonympha mitchellii

Distinguished from similar satyr butterflies by the combination of small size (34–44 mm wingspan), uniformly brown unmarked upper wing surfaces, and rows of round yellow-ringed eyespots on wing undersides. N. m. francisci differs from N. m. mitchellii in being slightly darker with more irregularly shaped eyespots. The Carolina satyr (Hermeuptychia sosybius) is similar in appearance but is a separate species; precise field identification may require close examination of wing pattern details.

Small brown butterfly with wingspan 34–44 mm. Upper wing surfaces unmarked. Undersides of wings display rows of round, yellow-ringed eyespots. N. m. francisci is slightly darker with more irregularly shaped eyespots. Eggs greenish white to cream, darkening to tan with age. First instar larvae 3–4 mm long with dark brown bilobed heads; subsequent instars 6–12 mm long with green bilobed heads, green bodies, and raised white lateral ridges. Chrysalis 10.5–15.5 mm long, light lime green with pale green or white speckling, suspended head-down; turns medium brown two days before eclosion.

Wetland habitats including prairie fens with alkaline, saturated soils, emergent vegetation, and scattered shrubs. N. m. mitchellii occurs in Michigan prairie fen ecosystems. N. m. francisci inhabits a restricted area within Fort Bragg, North Carolina.

Eastern United States. N. m. mitchellii: Michigan and Indiana; presumably extirpated from Ohio (last observed 1950s), New Jersey (last observed 1988), and Wisconsin. N. m. francisci: single metapopulation within a 10 × 10 km area at Fort Bragg, North Carolina. Additional populations discovered since 1998 in Alabama, Mississippi, and Virginia remain under taxonomic study.

Larvae feed on Japanese stilt grass (Microstegium vimineum), a highly invasive plant species.

• Microstegium vimineum - larval host plantJapanese stilt grass; invasive species

Eggs hatch after greenish white to cream eggs darken to tan. First instar larvae 3–4 mm with dark brown bilobed heads. Four subsequent instars 6–12 mm with green bilobed heads and green bodies with raised white lateral ridges. Chrysalis 10.5–15.5 mm long, suspended head-down, light lime green with pale speckling, turning medium brown two days before adult eclosion.

Federally endangered species protected under the Endangered Species Act. Subject of landscape conservation research examining habitat corridors and restoration effects on population viability. Populations potentially at risk from control efforts targeting the invasive Japanese stilt grass, which serves as a larval host plant.

• Hermeuptychia sosybiusSimilar appearance as a small brown satyr butterfly; both species can feed on Microstegium vimineum, but H. sosybius is a distinct species requiring close examination for differentiation

• endangered
• federally protected
• wetland specialist
• prairie fen
• invasive plant association

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Landscape Conservation for Rare Insects | Bug Squad
• Habitat Use by the Federally Endangered Mitchell's Satyr Butterfly (Neonympha mitchellii mitchellii) in a Michigan Prairie Fen
• Distribution, Population Structure and Habitat Use of the Endangered Saint Francis Satyr Butterfly, Neonympha Mitchellii Francisci