Compton Tortoiseshell (Nymphalis vaualbum) (Denis and Schiffermüller, 1775)
Diagnosis: This subtly beautiful butterfly is one of the largest of the subfamily (wingspan: 52 to 70 mm). Although resembling the anglewings, its larger size, and rich rust-brown colouring on the upperside readily distinguish it on the wing. The bases of the wings are dark brown. There is a thin, submarginal dark band with golden spots on the inner edge. On the hindwing upperside there is a single large black spot bordered toward the wing margin by white. The underside is marbled grey and brown, with a small white V in the centre of the hindwing representing the comma mark of the anglewings.
Subspecies: The nominate subspecies is Eurasian. The Canadian population is referred to as subspecies j-album. The western records have been treated as subspecies watsoni, but the differences are minute and this subspecies is not currently recognized.
Range: This species is circumpolar around the Northern Hemisphere. In North America, it is found in the northern U.S. and across Canada south of the tundra. However, it is known to wander and has been recorded as far as California and Florida to the south, and at Baker Lake, north of treeline in Nunavut, to the north.
Early Stages: The larvae are pale green and speckled, with branched black spines. They have spines on the head, as in Polygonia (see Butterfly Systematics) and the mid dorsal row of spines begins on the first abdominal segment. The larvae feed in groups on willow (Salix spp.), birch (Betula spp.), and poplar (Populus spp.).
Abundance: Not normally considered common, they can appear in large numbers some years. This butterfly is sometimes found in aggregations around wet spots on the ground.
Flight Season: Probably the longest-lived of Canadian butterflies in the adult stage. The single brood appears in July or August, hibernates as an adult, and can survive through until the following June.
Habits: The Compton Tortoiseshell is another woodland butterfly that is often associated with cottages in the Precambrian shield areas. It overwinters in tree cavities, under eaves, or in garages, outhouses, and cottages. In some years it can be rare or absent from an area.
Remarks: Although not to be expected, the Compton Tortoiseshell is sometimes seen in cities, like one seen flying near the Parliament Buildings in downtown Ottawa. It received its common name from Philip Henry Gosse, the famous English naturalist, who studied the life history of this butterfly when he lived in the town of Compton in the Eastern Townships of Quebec in the mid-nineteenth century.
© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.
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