Moths of North Carolina
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View PDFGeometridae Members:
Petrophora Members:
1 NC Records

Petrophora subaequaria (Walker, 1860) - Northern Petrophora Moth

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Taxonomy
Superfamily: Geometroidea Family: GeometridaeSubfamily: EnnominaeTribe: LithininiP3 Number: 91a1135 MONA Number: 6804.00
Comments: One of two species in this genus that occur in North America (Hodges et al., 1984), both of which have been recorded in North Carolina
Identification
Field Guide Descriptions: Covell (1984); Beadle and Leckie (2012)Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Forbes (1948)Technical Description, Immature Stages: Forbes (1948); Wagner et al. (2002)                                                                                 
Adult Markings: A medium-sized Geometrid, with pointed, light gray forewings (Forbes, 1948). The antemedian and postmedian are both pale gray -- lighter than the ground color -- and edged inwardly with brown; the subterminal is also bounded outwardly by a darker shade that fills the subterminal area. Both lines are fairly straight or slightly curved. In P. subaequaria, the postmedian intersects the costa at about 4/5 of the way out from the base, whereas in P. divisata, the postmedian reaches 5/6 of the distance; the ground color of divisata also has a pink tinge that is not present in subaequaria (Forbes, 1954). Species in the Erebid genus Ptichodis are also similar in wing shape and in the the configuration of their lines. However, those species have large reniform spots, not just the small discal spots present in P. subaequaria; their lines are also yellowish rather than pale gray.
Adult Structural Features: The antennae of both sexes are simple. The male valves in this genus have distinctive structures on the costa and juxta (Forbes, 1948), but no characters are given that separate the two species of Petrophora.
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: Forbes (1948) describes the larvae as slender, with a pale brown dorsal surface, blackish sides, and a clear white substigmatal area; fine pale dorsal stripes are also present, as are pale brown stripes on the venter (see also the description and illustration in Wagner et al., 2002). Forbes and Wagner et al. describe the larvae as strong jumpers.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: This is primarily a northern species with only a single record in the southern mountains of North Carolina
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)

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Flight Comments: Flies in May and June in the North (Forbes, 1948), which is consistent with our one record from May
Habitats and Life History
Habitats: The habitat was not recorded at its one North Carolina location.
Larval Host Plants: Oligophagous, feeding a several species of ferns (Forbes, 1948) including Bracken (Wagner et al., 2002) - View
Observation Methods: Comes to some extent to lights; larvae can be searched for by beating or sweep-netting ferns
Wikipedia
Status in North Carolina
Natural Heritage Program Status: SR
Natural Heritage Program Ranks: G4G5 SH
State Protection: Listed as Significantly Rare by the Natural Heritage Program. That designation, however, does not confer any legal protection, although permits are required to collect it on state parks and other public lands.
Comments: The presence of this species in the Southern Appalachians rests on a single historic specimen. It was not collected in the Great Smoky Mountains National Park All Taxa Biological Survey, nor has it been found in other surveys conducted in the mountains of North Carolina. As a fern-feeding species -- especially if it feeds on Bracken -- we would expect it to be fairly common in our area, or at least as common as a number of other northern disjuncts that have been documented in our mountains. More surveys are needed to give it a firmer place in our moth fauna and to better determine its conservation status.