Moths of North Carolina
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Pachysphinx Members:
2 NC Records

Pachysphinx modesta (Harris, 1839) - Big Poplar Sphinx

Superfamily: Bombycoidea Family: SphingidaeSubfamily: SmerinthinaeTribe: SmerinthiniP3 Number: 890148.00 MONA Number: 7828.00
Comments: This genus contains three similar species but members of the genus are quite unlike other Sphingids in our area.
Species Status: Bar coding indicates homogeneity of populations in the eastern half of the country but perhaps hidden species out west among Pachysphinx modesta and its replacement, P. occidentalis. In the West and Southwest, it blends into other species whose limits are unclear.
Field Guide Descriptions: Covell (1984); Beadle and Leckie (2012)Online Photographs: MPG, BugGuide, BAMONATechnical Description, Adults: Forbes (1948); Hodges (1971); Tuttle (2007)Technical Description, Immature Stages: Forbes (1948); Wagner (2005); Tuttle (2007)                                                                                 
Adult Markings: This large, greenish-brown moth with reddish pink hindwings is unique in the East. Sexes are similar.
Wingspan: 10 - 12 cm (Covell, 1984)
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: Larvae are large and stout, usually pale green but sometimes brown. The usual sphingid pattern of seven pale oblique lines are present on the sides, with the last one running up onto the short caudal horn. The body is covered with white granules (see Wagner, 2005, for details).
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Known in North Carolina only from a single record from Cabarrus County in the western Piedmont. Host plants occur more widely, particularly in brownwater floodplains in the Coastal Plain, but the species has not yet been recorded in that area.
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: Probably single brooded with adults in late May.
Habitats and Life History
Habitats: Unclear in North Carolina but Eastern Cottonwood -- the only species of Populus native to the area of the western Piedmont where this species has been recorded -- occurs primarily in riparian habitats. Exotic species are also present, either used in landscaping or escaping into disturbed areas. Pachysphinx has not been recorded in brownwater river floodplains where both Eastern and Swamp Cottonwoods are common.
Larval Host Plants: Stenophagous, possibly feeding solely on Cottonwoods and other Populus species. Once thought to also use Willows but efforts to find larvae on those species have failed (Tuttle, 2007).
Observation Methods: Adults are attracted to light but not flowers nor bait. Like other large Sphingids, it may be undersampled by use of 15 watt UV blacklights but may come better to high intensity UV sources, such as mercury-vapor.
See also Habitat Account for General Poplar Forests
Status in North Carolina
Natural Heritage Program Status: [SR]
Natural Heritage Program Ranks: G5 S1S2
State Protection: Currently not listed by the Natural Heritage Program but we recommend that it be rated as Significantly Rare. Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: In North Carolina, this species is likely a habitat specialist on Cottonwood-containing floodplains but has not been recorded in some areas with extensive areas of this habitat, e.g., the floodplains of the lower coursed of the Roanoke and Cape Fear Rivers. More surveys, making use of mercury-vapor lights, are needed to determine its distribution and conservation status in the state.

 Photo Gallery for Pachysphinx modesta - Big Poplar Sphinx

Photos: 1

Recorded by: Darryl Willis on 2022-08-08
Cabarrus Co.