Nymphalis antiopa

Distinguished from similar Nymphalis species by the combination of dark maroon ground color with yellow wing margins and blue submarginal spots. The California tortoiseshell (Nymphalis californica) has more orange-brown coloration with black spots rather than blue. Milbert's tortoiseshell (Aglais milberti) has a broad orange submarginal band. The mourning cloak's irregular wing margins and specific color pattern are unique among North American nymphalids.

Large butterfly with wingspan up to 100 mm. Dorsal wing surface dark maroon to brown with irregular pale yellow to cream-colored margins. Inner margin of yellow band marked by iridescent blue spots. Ventral surface gray with striated pattern and pale yellow edges. Body robust with reduced, brush-like front legs characteristic of Nymphalidae. Sexual dimorphism absent or minimal.

Hardwood forests, riparian corridors, and wooded parklands. In mountainous regions, occurs in cold, high-elevation areas. Adults often found near ravines, wood margins, lakes, ponds, and stream edges where males establish territorial perches. Larval habitat determined by presence of host plants, typically willows and other woody vegetation in moist or riparian settings.

Circumboreal distribution across northern hemisphere. Present throughout North America from Alaska and Canada south to northern South America, with reduced frequency in southern United States. Occurs across northern Eurasia from Europe through Russia to Japan. In Britain, appears as non-breeding migrant. Subspecies include N. a. antiopa (Europe), N. a. hyperborea (Canada, Alaska), N. a. lintnerii (eastern North America), and N. a. asopos (Japan).

Adults emerge from hibernation in late winter to early spring, often February–April depending on latitude. One brood per year in lowland areas; multiple broods possible in favorable conditions. Adults aestivate during summer heat, entering dormancy. Autumn generation migrates to overwintering sites. Overwintering adults reactivate in spring to mate and oviposit before leaves fully emerge.

Adults feed primarily on tree sap flows, especially from oaks; rotting and fallen fruits; and sugary exudates from aphid colonies. Nectar feeding from flowers is rare. Larvae feed on leaves of willows (Salix spp.), American elm (Ulmus americana), hackberry (Celtis occidentalis), hawthorn (Crataegus), wild rose (Rosa), birch (Betula), alder (Alnus), cottonwood and aspen (Populus).

• Salix nigra - larval food plantblack willow
• Salix pentandra - larval food plantbay willow
• Salix caprea - larval food plantgoat willow
• Ulmus americana - larval food plantAmerican elm
• Celtis occidentalis - larval food planthackberry
• Telenomus kolbei - egg parasitoidscelionid wasp, documented in France

Complete metamorphosis with four stages. Eggs laid in rings encircling terminal twigs of host plants, 0.7 × 0.9 mm, amber-yellow to olive-green maturing to lilac-pink and nearly black. Larvae gregarious, feeding communally in silken nests until final instar; black with reddish-orange dorsal spots, white speckling, and black spines, reaching 50 mm. Pupation in tan to gray chrysalis with red-tipped ventrolateral spines, suspended from grass stems, lasting approximately 15 days. Adults long-lived, entering reproductive diapause in summer and hibernating through winter.

Adults hibernate in tree cavities and beneath loose bark, often covered by snow. Males exhibit territorial behavior, defending perches against conspecifics and other insects. Polygynous mating system with males either lekking at display sites or engaging in scramble competition. Seasonal altitudinal migration observed: spring adults move upslope to breed in mountains, with offspring migrating downslope in late September–October. Adults bask with wings open to absorb solar heat. Defensive behaviors include camouflage by folding wings to resemble bark, playing dead, and producing audible clicks when disturbed.

Larvae function as herbivores on woody plants, occasionally causing localized defoliation. Adults serve as minor pollinators during rare nectar-feeding events. Adults are prey for birds, reptiles, amphibians, mammals, and invertebrate predators including mantids and dragonflies. Eggs parasitized by wasps including Telenomus kolbei. Larval aposematic coloration may contribute to predator education.

Occasional pest of ornamental trees in nurseries and parks when larval populations cause defoliation. Subject of long-term phenological research, including studies on climate change effects on emergence timing. Genome sequenced as part of Lepidoptera genomic research. State insect of Montana (adopted 2001). Cultural significance includes literary references and namesake of Camberwell district in London.

• Nymphalis californicaCalifornia tortoiseshell has orange-brown ground color with black spots rather than blue submarginal spots; more regular wing margins
• Aglais milbertiMilbert's tortoiseshell has broad orange submarginal band rather than yellow marginal band; smaller size
• Polygonia commaEastern comma has more angular wing margins, comma-shaped silver mark on ventral surface, and orange-brown coloration

• hibernating adult
• sap feeder
• gregarious larvae
• territorial behavior
• altitudinal migrant
• early spring flier

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Good Day, Mourning Cloak | Bug Squad
• 'Fourteen' Is a Lucky Number: That's Where the Monarchs Are | Bug Squad
• No Open House March 21 at Bohart Museum of Entomology | Bug Squad
• It's Over | Bug Squad
• No Contest, But Art Shapiro Spots First Cabbage White Butterfly of Year | Bug Squad
• Two Insect Contests: One Winner, One to Go | Bug Squad
• Interspecific Territorial Behavior of Two Mourning Cloaks (Nymphalis antiopa) in Response to a Diurnally Active Big Brown Bat (Eptesicus fuscus)
• Common name: mourning cloak (known in the United Kingdom as the Camberwell beauty) Nymphalis antiopa (Linnaeus) (Insecta: Lepidoptera: Nymphalidae: Nymphalinae)
• First record of Telenomus kolbei (Hymenoptera, Scelionidae) in France, parasitizing the eggs of Nymphalis antiopa and Aglais io (Lepidoptera, Nymphalidae)
• The genome sequence of the Camberwell Beauty, Nymphalis antiopa (Linnaeus, 1758) (Lepidoptera: Nymphalidae).