Mourning Cloaks cannot be confused with any other butterfly in BC, with their deep maroon to almost black colour, with a yellow border that fades to white with age. Males and females are almost identical, but the forelegs of males are hairier than those of females.
Mature larvae are black with rows of tiny white dots. Down the back is a row of bright red spots. There are rows of tubercles with black spines down the back and sides. The prolegs are dull red. Pupae are dark yellow brown, with blackish markings and reddish patches (Saunders 1869c; Scudder 1893; Sugden 1970).
The nominate subspecies occurs throughout BC. Subspecies hyperborea (Seitz, 1914) (TL: "extreme northern Alaska") does not occur in BC, and is a synonym of the nominate subspecies (Layberry et al. 1998). Specimens from Fairbanks, AK, considered to be hyperborea by Shapiro (1981c, 1981d), are identical to those throughout BC.
The name Nymphalis is linked to the Nymphales (nymphs), the name Linnaeus gave to a group of butterflies primarily consisting of present-day Nymphalinae. Both names were derived from the Greek numphe (a bride; a nymph all too often made a bride against her will by a lascivious god). The nymphs were lesser deities associated with springs, groves, mountains, and so on (Emmet 1991), a theme that was carried forward into genera such as Polygonia and Cercyonis. Linnaeus may have been referring to the forested habitats of many of the species in his Nymphales. The common name "tortoiseshells" refers to the resembance of the upperside of the wings of the butterflies to the mottled yellowish brown "tortoiseshell" of some sea turtles (Comstock and Comstock 1915) that is sometimes used for making combs. The name is shared with the genera Aglais and Roddia because the species in all three genera were originally placed in genus Aglais.
The butterflies in this genus are highly variable in wing pattern and colour, but they all share the same basic irregular wing margins, which includes a lobe on the hindwing resembling a small tail. Comparison of the dorsal and ventral wing patterns of each species shows that they share the same original pattern. Compton Tortoiseshells are now placed in the genus Roddia, as discussed earlier. Some authors also incorrectly place Milbert's Tortoiseshells in the genus Nymphalis rather than Aglais.
Tortoiseshells hibernate in hollow stumps and logs, debris piles, unheated buildings such as cabins and barns, and rock piles. There are seven species of Nymphalis worldwide.
Mourning Cloaks are univoltine in BC but are bivoltine in eastern Canada and Colorado (Brown et al. 1957; Layberry et al. 1998). Eggs are laid in cylindrical clusters surrounding a willow twig in the spring. The larvae live in an aggregation until the last instar, when they gradually disperse. There are typically about 100 eggs in a cluster, so the aggregations of larvae cause considerable defoliation of the willow plant on which they are feeding. Mature larvae drop or crawl off their larval foodplant, and wander considerable distances before pupating. They are frequently seen crossing streets and sidewalks at this time. Adults emerge from the pupae a couple of weeks after pupation, in July at low elevations.
At Tofino the first Mourning Cloak was collected hibernating in a woodpile in the mid-1930s; they were unknown before this. A few years later a massive population outbreak occurred in which all the willows on a small island in Tofino Inlet were completely defoliated and thousands of larvae crawled over the island searching for food. The outbreak has not been repeated, and Mourning Cloaks have remained present but uncommon around Tofino (AGG). The population outbreak may have resulted from colonization of the area by the species in response to land clearing, which promoted willow growth in an area originally dominated by conifers. Parasites may initially have been absent or rare, permitting a population outbreak of the butterfly.
Mourning Cloaks feed on poplar tree sap prior to hibernation, and hibernate in various sheltered locations, such as lumber piles and debris piles (CSG; JHS). When they emerge from hibernation on warm days in early spring, they feed on sap from stumps of recently cut trees (Saunders 1869c; CSG). Adults also feed on tree sap or in orchards on fruit juices, and are killed by orchard sprays (Atkinson 1978). Adults sometimes live a full year, with ragged hibernated adults still in flight when their freshly emerged offspring appear in flight (Cockle 1915).
Mourning Cloaks migrate in Europe, where it has long been known that they migrate to Great Britain but are
not permanent residents (Williams 1949a, 1949b). They also migrate south in the fall in eastern North America, using gliding and soaring flight between periods of flapping flight, in a manner similar to that of Monarchs (Gibo 1981). There is no indication that Mourning Cloaks migrate in western North America.
Larval foodplants in BC are willows (Salix scouleriana, S. babylonica, S. alba, and weeping willow), black cottonwood, trembling aspen, and ornamental elm (Harvey 1908; Jones 1942; Sugden, 1970; CSG; FIS). Outside BC other foodplants include Celtis occidentalis, Onobrychis vicifolia, Salix exigua, Salix jeppsoni, and S. bebbiana (Shapiro et al. 1981; Byers and Richards 1986; Scott 1992).
Mourning Cloaks are found throughout BC at all elevations. They are most often found in forest openings, especially along wet riparian areas in which willow grows.
Mourning Cloaks occur throughout much of Eurasia, and throughout subarctic, temperate, and subtropical North America south to northern South America.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2021-10-23 6:36:55 AM]
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