Moths of North Carolina
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View PDFGeometridae Members: 1 NC Records

Operophtera bruceata (Hulst, 1886) - Bruce Spanworm Moth


Taxonomy
Superfamily: Geometroidea Family: GeometridaeSubfamily: LarentiinaeTribe: OperophteriniP3 Number: 910282.00 MONA Number: 7437.00
Comments: One of three species in this genus recorded in North America north of Mexico (Troubridge and Fitzpatrick, 1993), and the only one recorded in North Carolina
Species Status: Bruceata is the only species in this genus native to eastern North America. However, the Winter Moth (O. brumata) has been spreading out from Canada and the Northeast, where it was introduced from Europe. That species is not yet recorded in North Carolina but is spreading out from its point of introduction and may eventually reach this far south, at least in the mountains.
Identification
Field Guide Descriptions: Beadle and Leckie (2012)Online Photographs: MPG, BugGuide, BOLDTechnical Description, Adults: Forbes (1948); Troubridge and Fitzpatrick (1993)Technical Description, Immature Stages: Forbes (1948); Wagner et al. (2001)                                                                                 
Adult Markings: A medium-sized, sexually dimorphic Wave. Females have greatly reduced wings and are flightless; males have fairly broad wings with rounded apices. The ground color of the forewings is pale brown in the East (gray in the West), with multiple dark brown lines that are usually sharply-defined and deeply scalloped (Troubridge and Fitzpatrick, 1993). Hindwings are also brown and crossed by multiple scalloped lines and a distinct discal spot is usually present. The abdomen is brown to golden brown. Operophtera brumata is similar in size and appearance but males usually have a reddish-brown ground color; have faint or more diffuse transverse lines that are only slightly scalloped; lacks a discal spot on the hindwings; and has a dark brown abdomen (Troubridge and Fitzpatrick, 1993). According to Troubridge and Fitzpatrick, all but badly worn specimens can be distinguished by wing markings and worn specimens can be identified by dissection.
Forewing Length: 12-16 mm, males (Troubridge and Fitzpatrick, 1993)
Adult Structural Features: Male reproductive structures are distinctive and are described and illustrated in Troubridge and Fitzpatrick (1993). The uncus of bruceata is usually very narrow, parallel-sided and not spatulate, contrasting with the broader and slightly spatulate case in brumata; females can be distinguished by wing length (see Troubridge and Fitzpatrick for more details).
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: Caterpillars are known as Bruce Spanworms or Cankerworms. They are typically green but can also be gray, brown, or black and white (Wagner et al., 2001). A well-defined, pale sub-dorsal line is present, along with two broken or faint lines on the side. Forbes (1948) mentions that the dorsal surface is darker, with the head, shields, and sides of the prolegs often blackish. Overwintering is done in the eggs stage; eggs are initially green then turning orange (Forbes, 1948).
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Our sole record comes from the northern mountains
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: Forbes (1948) reports that adults fly in the fall and early winter. Our one record corresponds with this range.
Habitats and Life History
Habitats: Our record comes from a stand of rich cove forest at about 3,400 (with higher peaks located close by)
Larval Host Plants: Polyphagous, feeding on many species of hardwood shrubs and trees, including a number that are associated with mesic montane forests. Wagner et al. (2001) specifically list alder, beech, birch, cherry, elms, hazelnut, maple, oak, serviceberry, willow, and witch hazel.
Observation Methods: As described by J.M. Lynch: "After over a week of no moths I had a big surprise waiting on the porch this morning--my first ever 7437 Operophtera bruceata (Bruce Spanworm)... It came to my regular porch light on a cold, rainy night (temp 37) after a week of snow and temps as low as 8. It pays to leave the porch light on!”
Wikipedia
See also Habitat Account for General Montane Mesic Forests
Status in North Carolina
Natural Heritage Program Status: W3
Natural Heritage Program Ranks: GNR SU
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: As appears to the case for several other of our montane species, bruceata may reach its southern range limit within the New River Valley of our northern mountains. Although it is likely a specialist on rich cove forests and northern hardwoods, it does not appear to be restricted in terms of its host plants and may be undersampled due to its extremely late flight period. Currently, not enough is known about its habitats, host plants, and other aspects of its distribution and ecology in North Carolina to make an accurate assessment of its conservation status. More surveys need to be conducted for adults in early winter and for larvae in the early spring.

 Photo Gallery for Operophtera bruceata - Bruce Spanworm Moth

Photos: 1

Recorded by: Merrill Lynch on 2013-12-03
Watauga Co.
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