Milbert's Tortoiseshell (Nymphalis milberti) (Godart, 1819)
Diagnosis: Another distinctively coloured, but smaller (wingspan: 34 to 52 mm) tortoiseshell. The basal part of the upperside of both wings is brown, with a broad bright orange to yellow band close to the wing margins. The hindwings have blue spots between the orange band and the irregular outer margin. There are two orange patches on the costa of the forewing in the dark basal area. The underside is dark brown in the basal area and lighter brown towards the margins.
Subspecies: The nominate subspecies milberti occurs over most of the Canadian range. Specimens from Newfoundland and extreme eastern Quebec (Bradore Bay) are larger than subspecies milberti and have virtually no yellow at the base of the orange marginal band; these are subspecies viola. Specimens from western Canada have, on average, more yellow at the base of the band than do eastern Canadian specimens and have been treated as subspecies furcillata. The difference, however, is only statistical and highly variable so we treat western Canadian populations as subspecies milberti.
Range: This species is widespread in Canada south of the tundra. It is common in Newfoundland, but there is only one record from Labrador at L'Anse-au-Clair near the Quebec border. It occurs on the coasts of James and Hudson Bays as far north as Churchill, Manitoba. In the west, it has been reported as far north as Norman Wells in the Northwest Territories.
Similar Species: None in Canada.
Early Stages:The young larvae live in communal nests on the foodplants, stinging nettles (Urtica spp.). The mature larva is black with branching spines on the back and sides. The middorsal row of spines begins on abdominal segment two. The larva is heavily speckled with small white flecks and orange spots that form a broken subdorsal line; there is a broken yellow lateral line along each side. Mature larvae live singly in folded leaf-nests.
Abundance: Milbert's Tortoiseshell is fairly common in most of its Canadian range and does not fluctuate as greatly in numbers from year to year as does the California Tortoiseshell.
Flight Season: This butterfly is on the wing from April to October, with possibly three overlapping generations. Specimens emerging from hibernation in the spring are usually quite pale and worn.
Habits: A quick, active species that flits rapidly about its territory, often along a woodland road. It regularly alights on the ground or on a rock or tree with its wings spread flat. It feeds mostly on sap, rotting fruit, and animal dung, but is also seen nectaring on flowers.
© 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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