Moths of North Carolina
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View PDFNepticulidae Members: 6 NC Records

Stigmella intermedia (Braun, 1917) - No Common Name


Taxonomy
Superfamily: Nepticuloidea Family: NepticulidaeSubfamily: NepticulinaeTribe: NepticuliniP3 Number: 160015.00 MONA Number: 72.00
Comments: Members of the genus Stigmella are a group of small leaf-mining moths that typically create linear mines, although a few species form linear-blotch or blotch mines. Newton and Wilkinson (1982) recognized 51 species in their revision on the North American fauna, and new discoveries have since raised the total to around 57 species. Almost all species are specialists and rarely use more than one genus of host plants. Host-specificity, mine characteristics, and genitalic differences are helpful in recognizing closely related forms that are externally similar.
Species Status: DNA barcoding indicates that Stigmella intermedia consists of two clades that might represent different species. Specimens that were collected from Rhus copallinum, R. glabra, and R. typhina in Vermont, Connecticut, Mississippi, and Alabama form a clade that represents S. intermedia as described by Braun (1917). Members of a second clade feed on R. aromatica, R. copallinum, R. typhina, and R. trilobata, and have been collected in Ontario, Quebec, South Dakota, and Colorado. This form is more closely related to the poison ivy feeder, S. rhoifoliella (Eiseman, 2019). North Carolina populations presumably belong to the first clade as described by Braun (1917).
Identification
Field Guide Descriptions: Online Photographs: BugGuide; iNaturalistTechnical Description, Adults: Newton and Wilkinson (1982)Technical Description, Immature Stages: Braun, 1917.                                                                                 
Adult Markings: The following description of the adults is based on Braun (1917) and Wilkinson and Scoble (1979). The palps are off-white and lustrous, and the antennae are slate gray and lustrous. The head and tuft are very dark brown to black, and the eye-caps are silvery white. The thorax is gray with silver and bronzy reflections. The ground color of the forewings is brownish black, and there are two white fasciae that shine silvery to light golden. The first fascia is sub-basal and often inconspicuous unless it is illuminated with the appropriate angle of light. The second is at about two-thirds the wing length and is conspicuous. The cilia is gray. The legs are gray and lustrous, and pale at the tarsi. This species is very closely related to S. rhofoliella, but has two fasciae on the forewing rather than a single fascia. The dark tuft will distinguish S. intermedia from S. prunifoliella, which has an orangish tuft.
Wingspan: 3.4-4.0 mm (Wilkinson and Scoble, 1979).
Adult Structural Features: The following description of the genitalia is from Wilkinson and Scoble (1979) Males: The tegumen is in the form of a narrow band. The saccus is large and bilobed, and the uncus is heavily sclerotized and cross-shaped. The gnathos is robust, with a pair of strong, posteriorly pointing horns that are well sclerotized at the tips, and a pair of small, anteriorly pointing lateral papillae. The valves are squared-off apically and not divided into a style and cuiller. The transtilla has the horizontal bar continuous; it is thin in the middle and thickens at the end. The aedeagus is fairly short. The vesica has cornuti in the form of stout spines near the phallotreme and a curved, striate rectangular plate. Females: The ductus bursae merges imperceptibly with the bursa. The bursa copulatrix has a few weak pectinations. The anterior apophyses are shorter and broader basally than the posterior apophyses. The latter are slightly longer, straight and narrow. The heavily sclerotized uncus and the shape of the gnathos of S. intermedia resemble those of S. prunifoliella. However, S. intermedla differs in the more deeply excavated saccus, the shape of the valves, and the fewer and larger spine-like cornuti on the vesica in the male genitalia. The bursa copulatrix of the female is only weakly pectinate. The genitalia of S. intermedia are indistinguishable from those of S. rhofoliella. However, the two species are readily separated by wing markings.
Immatures and Development: The egg is deposited on the lower leaf surface, and the bright green larva forms a linear mine on the upper surface (Eiseman, 2019). The mine is convoluted and slowly widens as the larva grows. The loosened epidermis is bright green at first, but turns yellowish with age. The mine has a broad blackish frass line that is nearly as broad as the mine, except near the emergence slit (Braun, 1917; Eiseman, 2019).


Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Stigmella intermedia occurs in the eastern US from Ohio eastward to Vermont, Connecticut, and Massachusetts, and southward to Pennsylvania, North Carolina, Mississippi, and Alabama. Populations in Canada, South Dakota, and Colorado appear to be genetically distinct, but are currently included within S. intermedia (Eiseman, 2019). As of 2020, our records are from the Coastal Plain and eastern Piedmont.
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: Braun (1917) noted that there are usually two generations a year in southern Ohio, but occasionally three. The larvae that mature in July overwinter.
Habitats and Life History
Habitats: This species is a specialist on sumacs (Rhus spp.), which are often found in rather open, sunny, habitats such as fencerows, roadsides, and recently abandoned fields. Sumacs also occur in natural habitats such as open woods, maritime forests, and rock outcrop communities.
Larval Host Plants: The larvae feed on sumacs (Robinson et al., 2010), including Fragrant Sumac (Rhus aromatica), Winged Sumac (R. copallinum), Smooth Sumac (R. glabra), and Staghorn Sumac (R. typhina). Our North Carolina records come from R. copallinum (Tracy Feldman, BugGuide, accessed 2020-01-03).
Observation Methods: The adults appear to rarely visit lights and almost all records are based on either leaf mines, or adults that were reared from mines.
Wikipedia
See also Habitat Account for General Sumac Thickets and Poison Ivy Tangles
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR S2S3
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: This species may be more common than our small number of records suggest because of minimal collecting effort within the state.

 Photo Gallery for Stigmella intermedia - No Common Name

Photos: 9

Recorded by: Dean Furbish on 2021-09-29
Wake Co.
Comment:
Recorded by: Jim Petranka and Becky Elkin on 2020-08-21
Madison Co.
Comment:
Recorded by: Tracy S. Feldman on 2018-06-22
Wake Co.
Comment: Unoccupied mines on Rhus copallinum--gradually-widening linear mines with central frass trail, mostly on upper side of leaves.
Recorded by: Tracy S. Feldman on 2018-06-22
Wake Co.
Comment: Unoccupied mines on Rhus copallinum--gradually-widening linear mines with central frass trail, mostly on upper side of leaves.
Recorded by: Tracy S. Feldman on 2017-10-09
Durham Co.
Comment: Unoccupied mines on Rhus copallinum--gradually-widening linear mines with central frass trail, mostly on upper side of leaves.
Recorded by: Tracy S. Feldman on 2015-07-21
Scotland Co.
Comment: Unoccupied mines on Rhus copallinum--gradually-widening linear mines with central frass trail, mostly on upper side of leaves.
Recorded by: Tracy S. Feldman on 2015-07-21
Scotland Co.
Comment: Unoccupied mines on Rhus copallinum--gradually-widening linear mines with central frass trail, mostly on upper side of leaves.
Recorded by: Tracy S. Feldman on 2015-07-21
Scotland Co.
Comment: Unoccupied mines on Rhus copallinum--gradually-widening linear mines with central frass trail, mostly on upper side of leaves.
Recorded by: T. DeSantis on 2013-09-20
Camden Co.
Comment: Leaf mines on winged sumac (Rhus copallinum).