Moths of North Carolina
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View PDFNoctuidae Members: 38 NC Records

Exyra ridingsii (Riley, 1874) - No Common Name


Taxonomy
Superfamily: Noctuoidea Family: NoctuidaeSubfamily: PlusiinaeTribe: PlusiiniP3 Number: 931190.00 MONA Number: 9023.00
Comments: One of three members of this genus, all of which are highly associated with the solely eastern North American genus of Pitcher Plants, Sarracenia. All three have been recorded in North Carolina.
Identification
Field Guide Descriptions: Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONATechnical Description, Adults: Jones (1921); Forbes (1954); Lafontaine and Poole (1991)Technical Description, Immature Stages: Jones (1921); Forbes (1954); Lafontaine and Poole (1991); Wagner et al. (2011)                                                                                 
Adult Markings: A medium-small, black-and-yellow striped Noctuid. The head and front half of the thorax are dark, blackish brown, differing from the crimson-and-yellow found in Exyra fax but very similar to the pattern shown by E. semicrocea. Unlike semicrocea, a strong, black antemedian line is usually present, strongly contrasting with the yellow ground color of the the basal and medial areas of the wing (sometimes extending beyond the postmedian). Similarly dark median and postmedian lines are often present, as well as a wider dark subterminal shade. Sometimes the bands are fused from the median outward to form a solid black outer portion of the wing. In these dark forms, the inner edge of the black portion is more curved or irregular than in semicrocea.
Adult Structural Features: Male and female genitalia are illustrated in Lafontaine and Poole (1991).
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: Mature larvae are wine red with white, intersegmental bands. Unlike Exyra fax but similar to E. semicrocea, elongated lappets (pinnacula or warts) occur on the thorax and anterior portion of the abdomen, that apparently help the larvae from getting stuck in the narrow bottom reaches of the pitcher plant tubes (Jones, 1921). In E. ridingsii, the lateral (= subdorsal) lappets on the thorax are longer than in semicrocea, approaching the lengths of those on the abdomen and longer than the dorsal warts on the same thoracic segments (Lafontaine and Poole, 1991; Wagner et al., 2011). The life history of the Exyra species was well-described by Frank Morton Jones, who studied them initially in Richmond County, NC (Jones, 1904). All life stages are closely associated with their host plants: eggs are laid within the entrance to the pitcher; larvae seal off the entrances to the tubes to create a sealed feeding chamber; both overwintering by larvae and pupation typically occurs within the bases of the tubes; and adults typically rest within the tubes between dispersive flights (see Jones, 1921, for details, including slight differences between species).
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Occurs in both the northern and southern Coastal Plain, including the Fall-line Sandhills. Formerly, at least, it was also recorded in several bogs in Montgomery County and in Wake County in the eastern Piedmont. However, it now appears to be extirpated from that region.
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
Immature 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: Possibly just a single adult flight in North Carolina, from May to July, with stragglers in August
Habitats and Life History
Habitats: All of our records come from peatlands, including Low Pocosin and Pocosin Openings; peaty areas in Wet Pine Savannas and Sandhill Seeps; and from boggy, sediment-filled portions of beaver ponds and other shallow impoundments. Always found in association with its host plant, Sarracenia flava.
Larval Host Plants: Monophagous, feeding solely on Yellow Pitcher Plants (Sarracenia flava) (Jones, 1907, 1921).
Observation Methods: Comes well to blacklights. Both adults and larvae can be found by inspecting the tubes of their host plants.
Wikipedia
See also Habitat Account for General Herbaceous Peatlands
Status in North Carolina
Natural Heritage Program Status: SR
Natural Heritage Program Ranks: G2G4 S2
State Protection: Listed as Significantly Rare by the Natural Heritage Program. That designation, however, does not confer any legal protection, although permits are required to collect it on state parks and other public lands.
Comments: This species, along with other members of this genus, is highly specialized on a habitat type that naturally had a extremely patchy distribution and that underwent a severe reduction in both its range and overall extent since European settlement due to conversion to croplands and pine plantations and to suppression of the natural fire regime. These trends, moreover, are still continuing. Surveys conducted by the Natural Heritage Program in 2009-2011 in the Sandhills and the Uwharrie Mountain region of the eastern Piedmont documented a particularly strong recent decline in Pitcher Plant populations. Even where a few plants have managed to survive -- or even where Sarracenia populations have recovered due to recent prescribed burning -- Exyra species could not be found, even where they had been seen as recently as the 1990s (S. Hall, upubl. data). While vigorous populations of Exyra ridingsii still exist on several large areas of habitat located on military lands, state parks, game lands, and private nature preserves, all of those are dependent on appropriate use of prescribed burning to support their metapopulations. At least one large tract of Low Pocosin and other peatland habitats -- located within the National Wildlife Refuges on the Albemarle-Pamlico Peninsula -- is highly threatened by salt-water intrusion associated with sea-level rise. Given these trends, this species has a high conservation concern in North Carolina, particularly in the Piedmont -- where it now may be completely extipated -- and the Fall-line Sandhills.

 Photo Gallery for Exyra ridingsii - No common name

Photos: 11

Recorded by: Alicia Jackson on 2019-07-31
Cumberland Co.
Comment:
Recorded by: Alicia Jackson on 2019-07-31
Cumberland Co.
Comment:
Recorded by: Jeff Beane on 2019-05-21
Pender Co.
Comment:
Recorded by: Jeff Beane on 2019-05-21
Pender Co.
Comment: Four adults observed inside tubes of Sarracenia flava
Recorded by: Jeff Beane on 2019-05-21
Pender Co.
Comment: Four adults observed inside tubes of Sarracenia flava
Recorded by: Steve Hall, Bo Sullivan, Tony McBride on 2014-06-24
Carteret Co.
Comment: Most Sarracenia flava tubes across a large area of this site showed feeding damage or contained larvae; no adults were seen
Recorded by: SPH on 1993-06-12
Montgomery Co.
Comment: photographed an adult inside a Sarracenia flava tube
Recorded by: Steve Hall on 1993-06-02
Cumberland Co.
Comment:
Recorded by: Steve Hall on 1993-06-02
Cumberland Co.
Comment:
Recorded by: Steve Hall on 1993-06-02
Cumberland Co.
Comment: When present, adults are easily found by flipping up the lids on Yellow Pitcher Plants and looking down the tubes. The moths are capable of moving up or down the tubes, unlike the normal victims of the Pitcher Plants, which are forced downward by the waxy surface and stiff hairs on the inside of the pitchers.
Recorded by: Steve Hall on 1993-06-02
Cumberland Co.
Comment: Pupa suspended on a silk hammock above the base of a Sarracenia flava tube. Holes are cut by the larvae to drain water collecting in the tube