Moths of North Carolina
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16 NC Records

Epiblema strenuana (Walker, 1863) - Ragweed Borer Moth

Taxonomy
Superfamily: Tortricoidea Family: TortricidaeSubfamily: OlethreutinaeTribe: EucosminiP3 Number: 621065.00 MONA Number: 3172.00
Comments: In their monograph and revision of Epiblema, Wright and Gilligan (2023) placed E. strenuana in the strenuana group and noted that most of the taxonomic history of this group has centered around whether this species and a closely related form, E. minutana, are distinct species or not. Various authors have treated them as being both conspecific and heterospecific since the early 1900's. In the most recent study, Gilligan et al. (2020a) treated them as separate species based on DNA barcoding, wing coloration, and the shape of the female sterigma.
Identification
Field Guide Descriptions: Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Gilligan et al. (2020a)                                                                                 
Adult Markings: In this species, the palps, frons, head, thorax and ground color of the forewings are all medium to dark brown. The interfascial spot in the middle of the wing is variably expressed and ranges from white to bronze. The paired costal strigulae on the distal half of the wing are whitish and usually inconspicuous in most individuals, except for strigula 9 near the apex (Wright and Gilligan, 2023). The associated gray striae extend toward the termen and are usually separated by lines of orangish-brown scales. Examination of genitalia may be needed for many specimens.

This species is most easily confused with Epiblema minutana, which is primarily brownish-gray to dark gray. The white costal strigulae are usually well expressed and there are no orangish-brown lines between the striae in the subcostal area near the apex. Epiblema minutana also has a whitish face and palps versus a brownish face and palps in E. strenuana. Female genitalia are also useful in separating the two species. Forewing length overlaps substantially between the two species, although on average E. strenuana is slightly larger (mean FWL = 7.1 mm for E. strenuana versus 6.0 mm for E. minutana).
Wingspan: 11-21 mm (Brown, 1973; McClay, 1987).
Forewing Length: 4.0-9.0 mm; mean = 7.1 mm (Wright and Gilligan, 2023).
Adult Structural Features: Wright and Gilligan (2023) and Gilligan et al. (2020a) have descriptions and illustrations of the male and female genitalia, and note that the male genitalia have socii that are long and fingerlike with lateral margins that are nearly parallel. In the female the sterigma is elongate and rectangular.
Adult ID Requirements: Identifiable only by close inspection of structural features or by DNA analysis.
Immatures and Development: Stegmaier (1971) reared specimens in Florida from larvae that were feeding on Common Ragweed (Ambrosia artemisiifolia). The larvae were stem borers that produced fusiform galls in the lateral branches of the mature plants. McClay (1987) documented the larval life history in northeastern Mexico where the larvae used Santa Maria Feverfew (Parthenium hysterophorus), which is an annual composite. After mating, the females attach their eggs either singly or in small groups to stems or leaves on the host plant. The hatchlings emerge after four days and initially feed briefly on axillary buds or other plant parts. They then bore into the stems, which triggers fusiform galls to form. Frass is initially ejected from the bore holes, but later is packed into the ends of the galls. The larvae feed within the galls and pass through six instars. The last instar then cuts a thin oval emergence window in the upper part of the gall and pupates. After the adult emerges the pupal exuvia is left protruding from the exit hole in the gall. McClay (1987) estimated the mean duration of the combined larval and pupal stages to last 28.5 days in one experiment that he conducted. In northwestern Mexico, this species overwinters as mature larvae, then pupate the following spring. There are two or three generations per year, with larvae present from March through November. McClay (1987) noted that galls were often formed when plants were in the rosette stage or had just begun to elongate, with gall formation slowing or preventing additional plant growth.
Distribution in North Carolina
Distribution: Epiblema strenuana is widely distributed across North America, including California, the central and eastern U.S. and adjoining areas of southern Ontario and Quebec. In the eastern U.S., populations occur from Maine southward to Florida, and westward to central Texas, Oklahoma, eastern Kansas, eastern Nebraska, Iowa, Minnesota and northeastern North Dakota. Scattered populations are also known from Colorado, Arizona, Utah, and Montana and the West Indies. As of 2024, we have scattered records from throughout the state, with most from the Sandhills.
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 fly year-round in Florida and mostly from April through September elsewhere. As of 2024, our records extends from early-April through late-August.
Habitats and Life History
Habitats: This species is generally associated with open, weedy habitats that support weedy annuals such as ragweeds.
Larval Host Plants: Ragweeds (Ambrosia spp.) appear to be the primary host in North America, particularly Common Ragweed (A. artemisiifolia), but also Giant Ragweed (A. trifida) and Weakleaf Bur Ragweed (A. confertiflora). Other members of the Asteraceae that are used include Santa Maria Feverfew (Parthenium hysterophorus) in Mexico and the West Indies, and cockleburs in Ontario (Heinrich, 1923; MacKay, 1959; Goeden and Rieker, 1976; McClay, 1987; Miller, 1987; Powell and Opler, 2007). - View
Observation Methods: The adults are attracted to lights and the larvae can be found in galls on members of the Asteraceae.
Wikipedia
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR [S3S4]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments:

 Photo Gallery for Epiblema strenuana - Ragweed Borer Moth

Photos: 13

Recorded by: David George, Jeff Niznik on 2023-07-09
Orange Co.
Comment: 		Recorded by: Jim Petranka on 2023-07-03
Madison Co.
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Recorded by: Stephen Dunn on 2023-06-18
Orange Co.
Comment: 		Recorded by: Stephen Dunn on 2023-05-31
Orange Co.
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Recorded by: Dean Furbish on 2023-05-31
Wake Co.
Comment: 		Recorded by: Dean Furbish on 2023-05-31
Wake Co.
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Recorded by: Stephen Hall on 2020-08-01
Orange Co.
Comment: 		Recorded by: Jim Petranka and Becky Elkin on 2020-06-02
Madison Co.
Comment:
Recorded by: Jim Petranka and Becky Elkin on 2020-06-02
Madison Co.
Comment: 		Recorded by: Harry Wilson on 2014-05-23
Wake Co.
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Recorded by: Harry Wilson on 2014-05-23
Wake Co.
Comment: 		Recorded by: Harry Wilson on 2013-08-24
Wake Co.
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Recorded by: T. DeSantis on 2012-08-17
Camden Co.
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