About Nymphalis antiopa (Linnaeus, 1758)
Nymphalis antiopa, called the mourning cloak in North America and the Camberwell beauty in Britain, is a large butterfly native to Eurasia and North America. Its immature stage is sometimes known as the spiny elm caterpillar. Older historical names for this species include grand surprise and white petticoat. This is a powerful flier, and migrating individuals are sometimes found in areas far from their usual range. Mourning cloak butterflies have a lifespan of 11 to 12 months, which is among the longest lifespans recorded for any butterfly. In 2001, this species was adopted as the state insect of the U.S. state of Montana.
Mourning cloak butterflies are widely distributed across the northern hemisphere. They are commonly found throughout all of North America and northern Eurasia. Three subspecies occur across North America: the northern subspecies Nymphalis antiopa hyperborea Seitz, 1913, the eastern subspecies N. a. lintnerii Fitch, 1857, and the southwestern subspecies N. a. thomsoni Butler, 1887. While they most often live in hardwood forests, they have been recorded in nearly every type of habitat. They can sometimes be found as far south as northern South America, and are rarely seen in southern U.S. states including Florida, Louisiana, and Texas. They are occasionally spotted in temperate regions of Asia, and a small number of individuals have even been recorded in Japan. Overall, mourning cloaks are most commonly found in cold, mountainous areas.
Most years, migrating individuals reach Great Britain during summer and autumn, but usually in very low numbers. There is no evidence that this species successfully breeds in Britain, and researchers believe mild, wet winters prevent individuals from surviving there for long. Butterfly farmer L. Hugh Newman raised thousands of Camberwell beauties for release at his farm in Bexley, but no individuals were seen the following spring. However, specimens he stored in a refrigerator over the winter did survive. In his writing, Newman noted that records of Camberwell Beauty captures in England were suspiciously concentrated around London, Hull and Harwich — all ports involved in timber trade with Scandinavia. He theorized the butterflies had hibernated in timber shipped to England, rather than traveling to Britain naturally.
Like all butterflies, mourning cloaks undergo complete metamorphosis, progressing through four life stages: egg, larva, pupa, and adult. Before host plant leaves begin to bud, female mourning cloaks lay their eggs in ring-shaped clusters around the terminal twigs of their host plants. Host plant selection is critical, as the plant provides food for hatching caterpillars. Females can produce multiple broods, typically up to two to three per individual. Newly hatched caterpillars stay grouped together until they shed their skin; each molt is called an instar. Four molts occur during development in a process called ecdysis, followed by a fifth molt that produces a fully grown caterpillar. Next, the caterpillar develops into a pupa and forms a tan or gray chrysalis that hangs from grass stems. The pupa stage is a period of rest and further maturation, and the full metamorphosis process from caterpillar to adult takes approximately fifteen days. Once development inside the chrysalis is complete, an adult mourning cloak butterfly emerges.
Research shows that mourning cloaks use the same endocrine mechanisms as other lepidopterans to regulate female-specific protein synthesis, oogenesis, and the development of both male and female reproductive glands. Juvenile hormone (JH) is involved in regulating oogenesis and reproductive gland development in both sexes of this butterfly.
Mourning cloak butterflies are not considered significant pollinators, because their primary food source is sap from deciduous trees rather than flowering plant nectar. However, they may occasionally act as pollinators.
When larvae first hatch, they begin feeding on the leaves of their larval host plants. A wide range of host plants have been recorded for this species, including multiple willow species (Salix nigra, Salix pentandra, Salix caprea, Salix aurita, Salix cinerea, Salix phylicifolia), American elm, hackberry, hawthorn, wild rose, multiple Betula species (Betula verrucosa, Betula chinensis), Alnus incana, and poplar. Caterpillars live gregariously in a shared silken nest on their host plant, and disperse before moving into the pupal stage. Adult mourning cloaks primarily feed on sap, ripe fallen fruit, and sugary aphid exudate, and are very rarely observed feeding on flower nectar.
