|scientific name Acronicta interrupta |
common name Interrupted Dagger Moth
Dry deciduous woodland edge and tall shrub.
A worn adult was collected in Alberta in mid August.
A medium-size (3.5-4.2 cm wingspan) pale grey moth. The forewings have a prominent black basal dash, which forks upward and downward at the antemedian line, and a thin, prominent black streak through a dark patch ("dagger-mark") in the anal angle. The cross-lines, with the exception of the postmedian line, are incomplete and indicated mainly by black marks where they meet the costa. The orbicular is a prominent pale spot narrowly outlined in dark scales. The reniform is vestigial, and consists of a dark marking the proximal side. The postmedian line is complete, s-shaped, doubled, and filled with white scales. The fringe is checkered, with the dark scales between the veins. The hindwing is dirty white in the male, darkening near the outer margin and along the outer veins, and light grey with a faint postmedian band in the female. Antennae in both sexes simple.
A solitary defoliator of deciduous trees and shrubs. There is a single annual brood that overwinters in the pupal stage. Adults come to light.
Rare, at the extreme western edge of it's range in southeastern Alberta.
A variety of deciduous trees and shrubs. No Alberta data, but elsewhere in Canada White elm (Ulmus americana) appears to be the main larval host, with the occasional record of pin cherry (Prunus pennsylvanicus), Ironwood (Ostrya virginiana), Mountain ash (Sorbus sp.), White and Yellow birch (Betula papyrifera and B. lutea), and willow (Salix sp.). Other hosts include apple (Malus sp.), oak (Quercus) and hawthorn (Craetagus).
Across southern Canada south of the Boreal forest, from New Brunswick west to eastern Alberta, south to GA, NE, and AR. In Alberta it has been collected only once to date (2001), in riparian shrub along the South Saskatchewan River near the Saskatchewan border, south of Empress. An eastern species that barely reaches Alberta in the dry southeastern part of the province.
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