Moths of North Carolina

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View PDF	Cossidae Members:	Prionoxystus Members:	120 NC Records

Prionoxystus robiniae (Peck, 1818) - Carpenterworm Moth

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, BOLD

Technical 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.


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: 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.

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