Identification
Adult: forewing mottled gray or grayish-brown and black with large white diagonal orbicular spot (occasionally filled with gray); AM and PM lines double, whitish, scalloped; reniform spot dark gray in center, whitish around perimeter; claviform spot conical; subterminal area dark gray with wavy or jagged ST line; terminal area light gray; fringe checkered with blackish triangles or semicircles between veins
hindwing brownish-gray, with darker shading distally, indistinct discal lunule, and pure white fringe
Larva: head creamy yellow with dark reticulation and prominent black middorsal and subdorsal stripes; body yellowish-brown with pair of prominent black triangular markings on dorsum of abdominal segments 7-8; spiracular stripe thin yellow with broad cream-colored subspiracular stripe below
[adapted from text at Canadian Forest Service]
Range
In North America: Greenland, Alaska, every province and territory of Canada, and south to New Jersey and Colorado (see
US distribution map)
In Eurasia: all of Europe and across Siberia to China and Japan (
Pacific Forestry Centre)
Habitat
bogs in northern coniferous forests; city gardens in Federicton NB
Season
adults fly from June or July to September
larvae from April to June
Food
larvae feed on leaves of birch, blueberry, cedar, Meadowsweet (Spiraea latifolia), snowberry (Symphoricarpos spp.), Sweet Gale (Myrica gale), tamarack, willow
Life Cycle
one generation per year; overwintering larvae become active in April, feeding until pupation occurs in June or July; adults emerge and lay eggs in late summer; eggs hatch in fall, and partially-grown larva overwinters
Remarks
"The moth that ate Greenland" -
short article on the Vikings' introduction of E. occulta to Greenland
See Also
Polia nimbosa and Polia propodea are similar but show no contrast between subterminal and terminal areas, their orbicular spot is darker, and their hindwing lacks a white fringe
Morrisonia latex and Polia imbrifera are also similar but have an indistinct PM line and a black anal dash, and their hindwing is lighter with no white fringe
Internet References
overview including description, habitat, biology, food plants, common name reference [Great Brocade], distribution, and links to adult and larva images (Robert Thompson and Brian Nelson, Butterflies and Moths of Northern Ireland)
pinned adult image plus description, food plants, distribution, and common name reference [Great Gray Dart] (Gerald Fauske, Moths of North Dakota)
live adult images of four specimens, plus food plant (Jens Christian Schou, Denmark, Moths and Butterflies of Europe and North Africa)
pinned adult images of male [top] and female, plus food plants, seasonality, synonyms, references, and links to other images (Finnish University & Research Network)
pinned adult image (Insects of Quebec)
live adult image plus food plants and info on migrant vs. resident individuals (Keith Dover, UK Moths)
pinned adult image plus food plant and other info (naturegrid.org.uk)
live larva image (Jim Porter, Butterflies and Moths of Northern Ireland)
live larva image (Roy Leverton, UK Moths)
live larva images and other info (Pacific Forestry Centre, Canada)
