Moths of North Carolina
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View PDFSaturniidae Members: 8 NC Records

Sphingicampa bicolor (Harris, 1841) - Honey Locust Moth



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Taxonomy
Superfamily: Bombycoidea Family: SaturniidaeSubfamily: CaratocaminaeP3 Number: 890024.00 MONA Number: 7709.00
Comments: One of two species in this genus found in our area (six others occur in the western US -- Tuskes et al., 1996). Despite the rarity of this species along the Atlantic Coast, the type locality for Sphingicampa bicolor is North Carolina (Ferguson, 1971).
Identification
Field Guide Descriptions: Covell (1984); Beadle and Leckie (2012; as Syssphinx bicolor)Online Photographs: MPG, BugGuide, BAMONATechnical Description, Adults: Forbes (1923), Ferguson (1971), Tuskes et al. (1996)Technical Description, Immature Stages: Forbes (1923), Ferguson (1971), Covell (1984), Tuskes et al. (1996), Wagner (2005)                                                                                 
Adult Markings: Both Forbes (1923) and Ferguson (1971) noted that Sphingicampa and Anisota species may be hard to tell apart. This is particularly true for the summer forms of S. bicolor, which resemble both A. stigma and senatoria in possessing a reddish or yellowish ground color, dark speckling, and a diffuse postmedian separating a darker medial area from a paler submarginal area. Where the hindwings are visible, Sphingicampa species have a basal patch of crimson or rose that strongly contrasts with the color of the forewing; in Anisota species, both sets of wings are similar in color. In photographs of living individuals, however, the hindwings may not be clearly visible and other characters need to be used. In a lateral view, the length of the inner margin (the edge next to the back when the wings are folded) is about the length or slightly longer than the outer margin (the edge located at the posterior end when the wings are folded); in Anisota, the inner margin is noticeably shorter (Forbes, 1923). The white discal spots are also often doubled in Sphingicampa but always single in Anisota; some individuals of Sphingicampa, however, show only a single spot or none at all. Finally, many bicolor (and some bisecta) show two dark streaks on the thorax, which is typically unmarked in Anisota species. The two Sphingicampas in our area also resemble one another but can be distinguished by the postmedian line: in S. bicolor, the postmedian is brown and fairly dffuse and terminates at the edge of the wing well in front of the apex; in S. bisecta, the postmedian is a finer, darker line that terminates close to or at the apex. S. bisecta also has a similar fine, dark antemedian line which is usually missing in S. bicolor.
Wingspan: 60-75 mm (Forbes, 1923)
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: Larvae of the two species of Sphingicampa are similar in color, spination, and identical in terms of host plants. Mature instar bicolor can be distinguished based on their possession of red tipped thoracic and abdominal horns, which are green in bisecta, and by a pronounced red-and-white lateral stripe, which is black-and-white in bisecta (Tuskes et al., 1996; Wagner, 2005). Ferguson (1971), however, observed a significant amount of individual variation in these traits. Pupation occurs in the soil.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Apparently has an extremely patchy distribution in North Carolina, although documented in the state since the early 1800s.
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: Triple-brooded in the Mid-west (Ferguson, 1971). In the eastern Piedmont, Parker Backstrom has records for adults from April through September, with possibly three distinct peaks: early spring, mid-summer, and late-summer/early fall. Ferguson noted that each brood has a distinctive primary color phase: brood one has predominantly grayish fore-wings and extensive areas of bright rose on the hind-wings; brood two has yellowish-brown fore-wings and much less extensive areas of rose on the hind-wings; brood three is browner/less yellow and more heavily spotted on the fore-wings and again has more extensive areas of rose on the hind-wings.
Habitats and Life History
Habitats: The naturalness of the habitats used by S. bicolor in North Carolina is uncertain, since neither of the two host plants recorded for this species is believed to be native here (Alan Weakley, pers. comm. to S. Hall, 2014). However, S. bicolor was recorded in the state in the early 19th Century, suggesting that Gleditsia (the most likely host) was present in sufficient quantities and distribution to sustain populations of the moth. While it is possible that most, if not all, of the populations recorded more recently have been associated with groves of Gleditsia planted around old homesites or escaped into pastures, the high concentration of Gleditsia-feeding moth species recorded in the vicinity of Goldston in Chatham County is difficult to account for based solely on random and highly infrequent colonizations from the Mid-west. A large sill of diabase occurs in that area along the Deep River floodplain and could provide at least an approximation of the calcium-rich floodplains that are some of the main habitat for Gleditsia, Gymnocarpus, and their associated moths in the Ohio and Mississippi Valleys. Whether this site actually represents a natural, relict habitat, however, needs much further investigation.
Larval Host Plants: Brimley (1938) lists Honey locust (Gleditsia triacanthos) and Kentucky coffeetree (Gymnocladus dioicus) as host plants. However, he did not mention any actual observations of larvae feeding on them in North Carolina and may have been referring to host plants known to be used in the Mid-west. Both of these trees are considered non-native introductions from the Mid-west and only Gleditsia occurs fairly widely, if sporadically, over most of the state.
Observation Methods: Comes to both blacklights and business lights fairly well; Parker Backstrom has observed up to three individuals at a time on several occasions. Adults do not feed, however, so do not come to bait. Sphingicampa larvae are reported to be fluorescent and can be searched for using blacklights (Stahnke, 1972, cited in Tuskes et al., 1996).
Wikipedia
See also Habitat Account for Honey Locust Groves
Status in North Carolina
Natural Heritage Program Status: W3
Natural Heritage Program Ranks: G5 S3?
State Protection: Currently placed on the NHP Watch List as W3: seemingly rare species that are too poorly known to assess their conservation status in North Carolina
Comments: The naturalness of the habitats used by this species still need to be assessed before its conservation status can be determined. If it makes use primarily of cultivated Gleditsia, particularly those commonly planted in parking lots, then its habitat may actually be increasing in the state. On the other hand, if it is associated with relict communities, such as mafic floodplain forests, then it could be highly vulnerable to extirpation.