Moths of North Carolina
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View PDFGeometridae Members: 2 NC Records

Stenoporpia polygrammaria (Packard, 1876) - Faded Gray Geometer



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Taxonomy
Superfamily: Geometroidea Family: GeometridaeSubfamily: EnnominaeTribe: BoarmiiniP3 Number: 910874.00 MONA Number: 6459.00
Comments: One of 23 species in this genus that occur in North America north of Mexico (Rindge, 1968; Hodges et al., 1984), most of which are western. Only one primarily Midwestern and Northeastern species reaches North Carolina.
Identification
Field Guide Descriptions: Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONATechnical Description, Adults: Forbes (1948); Rindge (1968); McGuffin (1977); Schweitzer et al. (2011)Technical Description, Immature Stages: Wagner et al. (2001)                                                                                 
Adult Markings: A medium-large Gray, with a whitish ground color shaded with light gray (Forbes, 1948; Rindge, 1968). The antemedian, median, and postmedian lines run parallel courses: curving in from the costa, making a strong bend at the cell, and running fairly straight and obliquely down to the inner margin. The postmedian and median run close together below the cell and the antemedian is also doubled. As in Protoboarmia, the lines are marked by a series of black denticles; small dark spots also mark the intersection of the lines with the costa (Rindge, 1968). Hindwings have a similar pattern, with the lines matching up with those on the forewing. The abdomen is banded dorsally with dark gray, but the dark and pale bands found in Anavitrinella and some Iridopsis on the first abdomninal segment are missing.
Wingspan: 35-40 mm (Forbes, 1948)
Forewing Length: 16-19 mm (Rindge, 1968)
Adult Structural Features: A fovea is present in the males but is much smaller than those of Anavitrinella pampinaria or Protoboarmia porcellaria, both of which have similar wing markings. The antennae of the males are pectinate but have a simple apex, again similar to that of Anavitrinella but differing from the completely and more broadly pectinate antennae of Protoboarmia. Male and female reproductive structures are distinctive and are described in Rindge (1968).
Structural photos
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: A larva illustrated in Wagner et al. (2001) is primarily gray with brown mottling. Diagnostic characters described by Wagner et al. include the nearly connected warts on the dorsum of segment A2, and the larger lateral ones on the same segment that include the spiracle. That pattern is repeated on A3, although the warts are smaller, and there are horn-like swellings on A8 (see Wagner et al., for additional details).
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Probably confined to the Blue Ridge and monadnocks in the Western Piedmont
County Map: Clicking on a county returns the records for the species in that county.
Flight Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

Click on graph to enlarge
Flight Comments: Schweitzer et al. (2011) state that there are two flights in North Carolina but do not provide any dates. Our records come from May and June.
Habitats and Life History
Habitats: The habitat at the Stokes County site consists mainly of Chestnut Oak Forest, dominated by Rock Chestnut Oak (Quercus montana), with other oaks, hickories, and pines in the canopy and blueberries dominating the shrub layer. A population of Bear Oak occurs further uphill from this site.
Larval Host Plants: Wagner et al. (2001) list both Red and White Oaks. Rindge (1968) stated that a Canadian larva was reared on Bur Oak (Quercus macrocarpa), a species that does not occur in our state. Schweitzer et al. (2011) suspected that Bear Oak (Quercus ilicifolia) might be the main host used in the Eastern United States, based on the association of the moth with barrens habitats where Bear Oak is a common to dominant constituent. Although the Stokes County site where one of our specimens was recorded contains a population of Bear Oak -- cited by Schweitzer et al. in support of their argument -- the moths were collected several hundreds of meters from where the oaks occurs and no Bear Oak is known to occur in the vicinity of the Avery County collection site. More information, consequently, needs to be obtained to determine what hosts are used in North Carolina.
Observation Methods: We have too few records to estimate how well this species comes to blacklights.
Wikipedia
See also Habitat Account for General Dry-Xeric Hardwood Forests
Status in North Carolina
Natural Heritage Program Status: SR
Natural Heritage Program Ranks: GU S1S2
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: This species has apparently declined drastically in the eastern portion of its range, and is now considered historic or extirpated from New England and New York. It is also apparently very scarce in North Carolina, where only a couple of records exist.