Compton Tortoiseshells are large orange brown butterflies with black markings. The underside of the wings has the pattern of lichens or dead leaves. The only somewhat similar butterflies are anglewings, which are much smaller. Males have a strongly variegated grey pattern on the underside of the wings; females have a plain brown wing underside, with the pattern of the males only weakly present. Male forelegs are very hairy, whereas the female foreleg is much less hairy, especially on the inner side.
Eggs are pale green and cylindrical, and have 11 heavy vertical ribs with many fine cross-ribs between them. First instar larvae are tan with a shiny black bilobed head, many black tubercles from which black hairs project, and dark brown legs. Mature larvae from Oliver, BC, have a dull black bilobed head covered with raised white tubercles tipped with hairs, and two spiny black tubercles rise from the top of the head. The body above the spiracles is initially black except for the last two segments, which are red brown, and gradually turns to light yellow brown blotched with darker brown as the larva matures. Down the back is a double row of white dashes, and there are numerous pale brown to white speckles and streaks on the sides. The white dashes down the back and the pale brown to white speckles and streaks on the sides all turn pale green as the larva matures. There is a thin lateral line of white dashes. The body below the lateral line is initially pale grey and brown, but turns pale green with pale brown blotches as the larva matures. There are spiny black scoli with black hairs on the back, which turn yellow brown as the larva matures. Pale brown green scoli on the sides turn pale green with white hairs. Pupae are pale green with pinkish highlights, and three pairs of silver-gold spots on each side of the back of the thorax (CSG). This is in reasonable agreement with the descriptions of Denton (1889) for larvae from Massachusetts, and Dawson (1889) for larvae from Montreal. The descriptions of mature larvae in the literature describe them as being pale green (e.g., Layberry et al. 1998). This is apparently derived from Lintner's description of a single prepupallarva (Scudder 1889a), which ignored the original descriptions of Denton and Dawson, and that single description was then repeatedly reproduced for more than 110 years.
Subspecies watsoni (G.C. Hall, 1924) (TL: Sicamous, BC) occurs in BC. It is more brown (less grey) on the underside of the wings than the eastern subspecies, j-album (Boisduval & Leconte, ) (TL: vicinity New York, Philadelphia, and New Harmony, IN).
The genus Roddia was named in honour of the Russian entomologist Evgenii Georgevich Rodd (Korshunov and Gorbunov 1995). The common name "tortoiseshells" is shared with the genera Nymphalis and Aglais because the species in all three genera were originally placed in the genus Aglais.
There is only a single species in this genus, the Compton Tortoiseshell, Roddia I-album, although it may eventually be demonstrated that the North American subspecies j-album is actually a separate species from the Asian I-album. Roddia I-album has traditionally been called Nymphalis vau-album (Denis & Schiffermüller, ). Compton Tortoiseshells are large, golden brown butterflies that are frequently very abundant in the BC interior, especially in the fall.
The genus Roddia Korshunov was described in 1995, with Papilio I-album Esper, 1780 as the type species (Korshunov and Gorbunov 1995). Roddia is more closely related to Polygonia than to Nymphalis, according to comparisons of mitochondrial and nuclear DNA (Soren Nylin, pers. comm.). This is supported by several characteristics it has in common with Polygonia: the white "comma" marking on the ventral hindwing, the sexual dimorphism in ventral wing colour, the pair of branched spines on the top of the head of the larva, and the branched mid-dorsal spines on all abdominal segments of the larva. As a result Roddia could be treated either as a subgenus of Polygonia or as a full genus. We have chosen to treat Roddia as a full genus because of differences from Polygonia, such as wing shape and genitalia that more closely resemble those of Nymphalis.
The species name I-album was generally used until dos Passos (1964) and Higgins and Riley (1970) treated the species as vau-album (Denis & Schiffermüller, ). The North American j-album was treated as a separate species until dos Passos (1964) placed it as a subspecies of vau-album. Koçak (1981) concluded that the species name vau-album is a nomen nudum, or "naked name," a name not attached to a specific taxon, by Article 12.1 of the International Code of Zoological Nomenclature. The first available valid name for the species is the traditionally used I-album Esper, 1780, which Koçak recommended be returned to use. Kudrna (1986) agreed with this approach, although Sattler and Tremewan (1984) and
Sattler (1989) disagreed on the grounds that vau-album was the accepted (modern) usage. Karsholt and Razowski (1996) followed Sattler's recommendation that all Denis and Schiffermüller names be retained "as the opposite view will have incalculable consequences for the stability of the nomenclature of European Lepidoptera." We disagree with this uncritical approach, preferring that of Kudrna (1986), in which each name is looked at individually, retaining only those Denis and Schiffermüller names that actually need to be retained for nomenclaturaI stability. The name vau-album is not one of those names.
The name I-album was in use for the 184 years between its description by Esper in 1780 and its rejection by dos Passos (1964), whereas the use of vau-album has still been disputed (e.g., Koçak 1981; Kudrna 1986) in the few decades since dos Passos (1964) and Higgins and Riley (1970). As a result of these changes in genus and species, Nymphalis vau-album is correctly called Roddia I-album.
Compton Tortoiseshells are univoltine, with adults hibernating. They are in flight from late July until they enter hibernation in October, and again from the time they leave hibernation in March until May. In the fall they commonly occur in very large numbers sitting in the middle of backroads and highways, with vehicles causing high mortality. Compton Tortoiseshells coming out of hibernation in a Quesnel barn in March 1999 consisted of 17 males and 28 females, suggesting higher male than female mortality (CSG). Oviposition occurs in April. Eggs are laid in small groups or short lines near the tip of twigs of birch whose leaves are just beginning to expand. Females bask head up in the sun while ovipositing and between oviposition episodes. When the eggs hatch, the larvae remove a neat disc from the top of the egg, and do not eat the egg chorion. The first and second instars are gregarious, whereas the third to fifth instars are solitary. All larval instars produce silk. In the fall near Attachie in the Peace River area of BC, JHS observed a Compton Tortoiseshell flying directly to a source of tree sap as though returning to a known site, and feeding there. Nectar sources were abundant, hence the butterfly was apparently choosing sap over nectar.
The only larval foodplants known in BC are water birch and paper birch (CSG; FIS). Outside BC, willow and trembling aspen have also been reported (Denton 1889; Holland 1931; Ferris and Brown 1981).
Compton Tortoiseshells occur throughout the BC mainland east of the coastal mountains, with occasional strays on the coast. They are most common in forest openings, and can be extremely abundant along logging roads in the fall.
Compton Tortoiseshells occur in Eurasia, and in North America from western BC across boreal CAN and the northern USA to NF. They frequently migrate far north into the arctic, and far south into the southern USA.
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:
2021-09-23 4:34:04 PM]
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