Moths of North Carolina

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View PDF	Sesiidae Members:	Carmenta Members:	37 NC Records

Carmenta bassiformis (Walker, 1856) - Ironweed Clearwing

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Taxonomy

Superfamily:
Sesioidea

Family:
Sesiidae

Subfamily:
Sesiinae

Tribe:
Synanthedonini

P3 Number:
55a0139

MONA Number:
2596.00

Other Common Name:
Eupatorium Borer Moth

Comments: Of the 136 or more members of the Sesiidae that occur in North American north of Mexico, 37 have been recorded in North Carolina. Some sesiids, known broadly as clearwing borers, are significant pests of commercial crops. The great majority are mimics of wasps and hornets.

Identification

Field Guide Descriptions: Covell (1984); Beadle and Leckie (2012)

Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLD

Technical Description, Adults: Eichlin and Duckworth (1988)

Adult Markings: The following description is based primarily on that of Forbes (1923) and Engelhardt (1946). In the males, the antenna is black with bluish reflections and often has a short area of buff shading near the tip. The palp is pale yellow with a blackish tip, while the head is black and the collar yellow. The thorax varies from black to bluish-black or coppery and has a long, thin, yellow stripe along the sides, along with tufts of yellow scales that extend from the metathorax. The black to violaceous-black abdomen is long and slender, and has fine yellow stripes on segments 1 to 4 and typically on 6 and 7. The large, fan-shaped, anal tuft is mostly lustrous black with yellow along the sides and through the center on the undersides. The forewing is transparent, with a narrow, metallic bronzy border, while the outer margin is rounded inwardly with dull, yellowish rays between the veins. The oblong discal mark is purplish-black and relatively straight. The hindtibia is yellow below, often mostly black above, while the tarsi are mostly yellow, with darker scaling often present on the joints. Females are generally similar, but the antenna has a more conspicuous buff to yellowish or whitish area before the tip, and the discal mark on the forewing is bronzy-brown instead of black. The abdomen in broader than that of the male, and there are two or three broad yellow bands that contrast with the remaining bands that are much narrower (segment 5 lacks banding altogether). The anal tuft is short and blunt relative to that of the male, and has black at the base, with orange to yellowish scales at the tip.

Carmenta bassiformis is most easily confused with C. ithacae. The latter tends to have the light mark on the antenna, the bands on the abdomen, the occiput fringe, and the lateral fringe on the anal tuft more whitish or yellowish-white, although the antennal mark on female C. bassiformis is often whitish. Female C. ithacae lack the prominent yellowish tip of the anal brush as seen in female C. bassiformis, and the whitish region below the tip of the antenna is generally shorter than that of female C. bassiformis. Both sexes of C. ithacae have hind tarsi with long black bands that alternate with shorter yellowish or whitish bands. In C. bassiformis, males have yellow hind tarsi while the females have alternating dark and yellowish bands on the tarsi, with the dark bands less prominent and boldly contrasting than those of C. ithacae. In addition, C. ithacae lacks the powdered yellow scales on the coxa and legs that are seen on C. bassiformis. Size differences for a given sex are also useful, with C. bassiformis being larger and having minimal size overlap with C. ithacae.

Wingspan: 18-21 mm for males; 18-26 mm for females (Engelhardt, 1946).

Forewing Length: 6-12 mm (Brown and Mizell, 1993).

Structural photos

Adult ID Requirements: Identifiable from good quality photos of unworn specimens.

Immatures and Development: Engelhardt (1946) provided a detailed life history of this species, and noted that the larvae are root borer in New York Ironweed (Vernonia noveboracensis) and other related ironweeds. In New York and vicinity the adults are often common and appears to live in widely-separated colonies. They emerge in this region beginning in late-July. After mating, the females deposit eggs singly or in small numbers by either attaching these to leaves, or dropping them at the base of ironweeds. The young larvae enter growing stems, then bore down to the roots where they feed. The larvae overwinter in the roots and resume feeding during spring and early summer. Before pupating, the larvae leave the roots and enter the lower portions of the dead stems of the previous year’s growth. They then girdle the stems, which causes them to break off a short distance above the ground. Pupation occurs within the old stem stumps.

Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.

Distribution in North Carolina

Distribution: Carmenta bassiformis is primarily restricted to the eastern US and in fringing areas of southern Ontario. In the US, the range extends from Connecticut and New York southwestward through the Piedmont and Appalachian region to Georgia and Alabama, and westward to eastern Texas, Arkansas, Missouri, Iowa and southern Wisconsin. This species is absent from most of the southeastern Coastal Plain. As of 2024, all of our records are from the Piedmont and lower elevations in the 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: The adults have been observed from May through September in different areas of the range. As of 2024, our records extend from early-June to late-August, with Blue Ridge populations having a longer flight period compared to those in the Piedmont.

Habitats and Life History

Habitats: Local populations are generally associated with mesic edge habitats, old fields, openings in bottomland sites and similar habitats that support rank weedy perennials.

Larval Host Plants: The larvae feed on species of ironweed (Vernonia) and possibly Joe-Pye-weeds (Eutrochium) (Forbes, 1923; Engelhardt, 1946; Covell, 1984). The reported hosts include Sweet Joe-pye-weed (Eutrochium purpureum), Arkansas Ironweed (V. arkansana), and New York Ironweed (V. noveboracensis). Surprising little work has been done to document the host plants since Engelhardt's (1946) work in New York. Engelhardt (1946) was unable to locate any larvae that were feeding on Joe-pye-weed, and questioned whether members of this genus are used as hosts. We do not have any feeding records in North Carolina. - View

Observation Methods: The adults are not attracted to lights. They are diurnal and can be found on flowers or resting on the upper surfaces of vegetation during the day. They are most active during the warmer hours of the day when they nectar on flowers, and can be found resting on foliage in the morning and late in the afternoon. The males are attracted to pheromone traps.

Wikipedia

Status in North Carolina

Natural Heritage Program Status:

Natural Heritage Program Ranks:

State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.

Comments:

Photo Gallery for Carmenta bassiformis - Ironweed Clearwing

36 photos are available. Only the most recent 30 are shown.

	Recorded by: Jim Petranka on 2025-07-15 Madison Co. Comment: Specimen dissected; male; FWL = 9.5 mm.		Recorded by: Jim Petranka on 2025-07-15 Madison Co. Comment: Specimen dissected; male; FWL = 9.5 mm.
	Recorded by: Jim Petranka on 2025-07-15 Madison Co. Comment: Specimen dissected; male; FWL ca. 7.0 mm for both.		Recorded by: Jim Petranka on 2025-07-15 Madison Co. Comment: Specimen dissected; male; FWL ca. 7.0 mm for both.
	Recorded by: Nora Murdock, Robert Emmott on 2024-08-14 Haywood Co. Comment:		Recorded by: Nora Murdock, Robert Emmott on 2024-08-14 Haywood Co. Comment:
	Recorded by: forest-stream-and-sea on 2024-06-23 Buncombe Co. Comment: Creative Commons: (CC BY-NC); a male.		Recorded by: forest-stream-and-sea on 2024-06-23 Buncombe Co. Comment: iNat: Photo 399318139; male; Creative Commons: (CC BY-NC)
	Recorded by: tom ward on 2023-08-06 Buncombe Co. Comment:		Recorded by: Ken Kneidel on 2023-06-07 Mecklenburg Co. Comment:
	Recorded by: Simpson Eason on 2022-06-23 Durham Co. Comment:		Recorded by: David George, Becky Watkins on 2022-06-13 Durham Co. Comment:
	Recorded by: David George, Becky Watkins on 2022-06-11 Orange Co. Comment:		Recorded by: David George, L.M. Carlson, Becky Watkins on 2022-06-09 Orange Co. Comment:
	Recorded by: David George on 2022-06-08 Orange Co. Comment: Female.		Recorded by: David George on 2022-06-08 Orange Co. Comment:
	Recorded by: Jim Petranka on 2021-07-30 Madison Co. Comment:		Recorded by: Jim Petranka on 2021-07-30 Madison Co. Comment:
	Recorded by: Jim Petranka on 2021-07-30 Madison Co. Comment:		Recorded by: ragbird on 2021-07-11 Mecklenburg Co. Comment:
	Recorded by: John Gerwin on 2021-07-01 Wake Co. Comment: Male.		Recorded by: David George on 2021-06-30 Orange Co. Comment:
	Recorded by: Owen McConnell on 2021-06-29 Durham Co. Comment:		Recorded by: David George on 2021-06-24 Durham Co. Comment:
	Recorded by: David George on 2021-06-24 Durham Co. Comment:		Recorded by: Barbara McRae on 2020-08-30 Macon Co. Comment:
	Recorded by: Lior Carlson on 2020-06-20 Orange Co. Comment:		Recorded by: Simpson Eason on 2019-06-26 Durham Co. Comment:
	Recorded by: Jim Petranka and Becky Elkin on 2019-06-21 Madison Co. Comment: Determined by J.B. Sullivan based on dissection.		Recorded by: Jim Petranka and Becky Elkin on 2019-06-21 Madison Co. Comment: