Moths of North Carolina
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View PDFCossidae Members: Prionoxystus Members: 120 NC Records

Prionoxystus robiniae (Peck, 1818) - Carpenterworm Moth


Prionoxystus robiniaePrionoxystus robiniaePrionoxystus robiniaePrionoxystus robiniae
Taxonomy
Superfamily:
Cossoidea
Family:
Cossidae
Subfamily:
Cossinae
Tribe:
[Cossini]
P3 Number:
53a0029
MONA Number:
2693.00
Other Common Name:
Robin's Carpenterworm
Comments: One of three members of the genus in North America, two of which are found in North Carolina. It is among the largest of the "micro-moths."
Identification
Field Guide Descriptions: Covell (2005); Beadle and Leckie (2012)Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Forbes (1923)Technical Description, Immature Stages: Packard (1890)                                                                                 
Adult Markings: Sexually dimorphic. Both sexes possess a thick abdomen, broad thorax, and disproportionally small head with pectinate antennae. The forewings of the female are black and heavily mottled with black-centered gray spots and blotches, while the hindwings are translucent gray. Males are smaller with narrower, more attenuated forewings that show similar markings but appear noticeably blacker overall. The hindwings of the male have a straighter outer margin and are reddish-orange to yellow, bordered in black. Differentiated from P. macmurtrei by less translucent gray-spotted rather than black-striated forewings.
Wingspan: 50-75 mm (Forbes, 1923)
Adult Structural Features: Length from tip of head to apex of forewing at rest averages 44.5 mm (n=2) (female).
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The larvae are known as carpenterworms for their wood-boring habits. Early instars are reddish-pink with dark brown thoracic segments and heads. Last instar is large (up to 3 inches) and greenish-white, with pink shading, raised reddish bumps along the dorsum and sides, reddish, oval spiracles, and a dark brown head and thorax. Because they develop in wood, larvae are rarely seen, although the exit holes can be seen scarring tree trunks. This species can be a serious pest in ornamental or agricultural settings.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Probably occurs statewide
County Map: Clicking on a county returns the records for the species in that county.
Prionoxystus robiniaeAlamance Alexander Alleghany Anson Ashe Avery Beaufort Bertie Bladen Brunswick Buncombe Burke Cabarrus Caldwell Camden Carteret Caswell Catawba Chatham Cherokee Chowan Clay Cleveland Columbus Craven Cumberland Currituck Dare Davidson Davie Duplin Durham Edgecombe Forsyth Franklin Gaston Gates Graham Granville Greene Guilford Halifax Harnett Haywood Henderson Hertford Hoke Hyde Iredell Jackson Johnston Jones Lee Lenoir Lincoln Macon Madison Martin McDowell Mecklenburg Mitchell Montgomery Moore Nash New%20Hanover Northampton Onslow Orange Pamlico Pasquotank Pender Perquimans Person Pitt Polk Randolph Richmond Robeson Rockingham Rowan Rutherford Sampson Scotland Stanly Stokes Surry Swain Transylvania Tyrrell Union Vance Wake Warren Washington Watauga Wayne Wilkes Wilson Yadkin Yancey
Flight Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

Click on graph to enlarge
Image showing flight dates by month for High Mountains greater than 4,000 feet, Low Mountains, Piedmont, and Coastal Plain: adults.
Flight Comments: Appears to have one main flight, from April to early August in North Carolina
Habitats and Life History
Habitats: Most of our records come from stands of hardwoods growing in bottomlands or mesic slopes. A few, however, come from xeric sites, including maritime forests, sandhills, and dry ridge tops.
Larval Host Plants: The larvae bore into the wood of a wide variety of deciduous trees (Forbes, 1923; Craighead et al., 1950; English, 1958; Prentice, 1966; Baker, 1972; Covell, 1984; Covell, 2005; Heppner, 2007; Robinson et al., 2010). The reported hosts include Box-elder (Acer negundo), Groundsel-tree (Baccharis halimifolia), American Chestnut (Castanea dentata), Sweet Chestnut (C. sativa), Sugarberry (Celtis laevigata), fig (Ficus), Green Ash (Fraxinus pennsylvanica), Balsam Poplar (Populus balsamifera), Eastern Cottonwood (P. deltoides), Quaking Aspen (P. tremuloides), White Oak (Quercus alba), Turkey Oak (Q. laevis), Live Oak (Q. virginiana), Black Locust (Robinia pseudoacacia), willows (Salix), American Elm (Ulmus americana), and English Elm (U. procera). - View
Observation Methods: Both sexes attracted to lights, though females are seen more commonly than males. Since the mouthparts of the adults are rudimentary, they do not feed and consequently do not come to bait or visit flowers
Wikipedia
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: G5 [S5]
State Protection: Has no legal protection, although permits are required to collect it in state parks and on other public lands.
Comments: This species is widespread in North Carolina and uses a wide variety of habitats, some very common. Consequently, it appears to be secure within the state.

 Photo Gallery for Prionoxystus robiniae - Carpenterworm Moth

92 photos are available. Only the most recent 30 are shown.
Prionoxystus robiniaeRecorded by: Jim Petranka on 2025-06-20
Madison Co.
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Prionoxystus robiniaeRecorded by: Jeff Niznik, David George, Larry Chen, Sarah Toner, Joye Zhou on 2025-06-20
Richmond Co.
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Prionoxystus robiniaeRecorded by: Mark Basinger on 2025-05-03
Brunswick Co.
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Prionoxystus robiniaeRecorded by: Giuseppi Betta on 2025-04-23
Anson Co.
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Prionoxystus robiniaeRecorded by: Mark Basinger on 2025-04-19
Brunswick Co.
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Prionoxystus robiniaeRecorded by: Mark Basinger on 2025-04-19
Brunswick Co.
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Prionoxystus robiniaeRecorded by: Owen McConnell on 2024-06-28
Graham Co.
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Prionoxystus robiniaeRecorded by: Mark Basinger on 2024-06-24
Yancey Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2024-06-10
Madison Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2024-06-10
Madison Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2024-06-06
Madison Co.
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Prionoxystus robiniaeRecorded by: Michael P. Morales on 2024-05-31
Cumberland Co.
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Prionoxystus robiniaeRecorded by: Michael P. Morales on 2024-05-31
Cumberland Co.
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Prionoxystus robiniaeRecorded by: Simpson Eason on 2024-05-28
Durham Co.
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Prionoxystus robiniaeRecorded by: Mark Basinger on 2024-05-22
Wilson Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2024-05-20
Madison Co.
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Prionoxystus robiniaeRecorded by: Stephen Dunn on 2024-05-20
Orange Co.
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Prionoxystus robiniaeRecorded by: Mark Basinger on 2024-05-19
Rowan Co.
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Prionoxystus robiniaeRecorded by: Mark Basinger on 2024-05-19
Rowan Co.
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Prionoxystus robiniaeRecorded by: Simpson Eason on 2024-05-17
Durham Co.
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Prionoxystus robiniaeRecorded by: Simpson Eason on 2024-04-19
Durham Co.
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Prionoxystus robiniaeRecorded by: tom ward on 2023-07-11
Buncombe Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2023-07-03
Madison Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2023-06-28
Madison Co.
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Prionoxystus robiniaeRecorded by: L. Knepp on 2023-06-21
Surry Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2023-06-06
Madison Co.
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Prionoxystus robiniaeRecorded by: Jim Petranka on 2023-06-05
Madison Co.
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Prionoxystus robiniaeRecorded by: David George, Stephen Dunn, Jeff Niznik on 2023-06-03
Orange Co.
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Prionoxystus robiniaeRecorded by: David George, Jeff Niznik on 2023-05-17
Chatham Co.
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Prionoxystus robiniaeRecorded by: David George, Jeff Niznik on 2023-05-17
Chatham Co.
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