Syngrapha microgamma (Hübner, 1823)

93-1230

Identification

Adults

Syngrapha microgamma is a small (FW length 13 -14 mm) gray and black moth with an ornate silver-white stigma on the mid-wing and a yellow and black hindwing that flies in bogs in British Columbia in late spring and early summer. The forewing is slightly pointed, has a scalloped fringe, and a small flange at the anal angle. The ground color is mottled gray, darkest on the costa in the median area and on the anterior two-thirds of the distal margin and lighter blue-gray in the anterior subterminal area and posterior terminal area. The median area posterior to the cubital vein is smooth velvety black or brown-black, slightly suffused with blue-gray toward the trailing margin. The stigma is fairly ornate, comprised of a basal squiggly V shape, thickest inferiorly, and a lateral thick oval or round projection that sometimes is a separate satellite spot. The basal, antemedial, and postmedial lines are gray to black, double, with gray, silvery filling, or light yellow filling. The basal line is dark gray or black, evident on the anterior two-thirds of the wing. The antemedial line is a dark gray bar on the costa and a black and silver incurved line below the cubital vein. The median line is a dark smudge near the reniform spot. The postmedial line is gray filled with light gray to cream near the costa and black filled with light yellow adjacent to the black median area. It is oriented perpendicular to the trailing margin and is irregular. The subterminal line is dark gray, nearly black on the anterior wing, irregular and nearly touching the outer margin below the apex and on the mid-wing near vein CuA1. The terminal line is pale gray medially with dark spots between the veins at the margin. The fringe is blue-gray with dark gray checkering.

This species can be identified by the combination of small size, gray and black forewing color, stigma with a thick rounded lateral projection or satellite spot, and yellow and black hindwing. Other Syngrapha species with yellow and black hindwings are brown (Syngrapha ignea and Syngrapha alticola) or larger with gray forewings that lack this feature of the stigma (Syngrapha borea and Syngrapha orophila).

A similar but smaller species, Syngrapha montana, is a predominantly eastern North American species that has been found in Saskatchewan and Alaska in the West and might conceivable occur in northern British Columbia. It is smaller than S. microgamma (FW length 12 -13 mm), tends to have a darker gray forewing with a subterminal line that is similar in strength across the entire wing rather than darker anteriorly, and has a thinner lateral extension of the stigma. Definitive identification requires examination of the genitalia as described in Lafontaine and Poole (1991).

Larvae

Larva is smooth with only two pairs of abdominal prolegs.  The color is green, changing to reddish brown in older instars, with a very broad white lateral band.  It is illustrated by Lafontaine & Poole (1991).

Habitat

This species is widely distributed across Canada in boreal spruce-fir forests and wet tundra, preferring acid bogs in British Columbia.

Distribution

Pacific Northwest

Syngrapha microgamma has been collected in northern and south-central British Columbia in the Northwest.

Global

This is a Holarctic species that is found across the Northern Hemisphere

Life History

Larvae

This species is a foodplant specialist feeding on various Ericaceae such as huckleberries (Vaccinium spp.), but appears to particularly favor Labrador tea (Ledum groenlandicum) as a larval foodplant.

Adults

The summer flight period of S. microgamma is relatively short at any locality, usually occurring from late May to late July. It is both diurnal and nocturnal.

Economic Importance

None.

Literature

BugGuide

Lafontaine & Poole (1991)