Moths of North Carolina
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Phyllocnistis Members:
37 NC Records

Phyllocnistis magnoliella Forbes, 1923 - Magnolia Serpentine Leafminer Moth



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Taxonomy
Family: GracillariidaeSubfamily: PhyllocnistinaeP3 Number: 330404.00 MONA Number: 851.00
Comments: Phyllocnistis liriodendronella and P. magnoliella are the only species of Phyllocnistis in our area that have a longitudinal golden streak from the base to the middle of the forewing. According to Forbes (1923), brown edging occurs along the golden streak in P. liriodendronella, but is absent in P. magnoliella. Forbes also noted that P. liriodendronella is a specialist on the Tuliptree (Liriodendron tulipifera), while P. magnoliella specializes on several species of native magnolias (Magnolia). Eiseman (2019) raised specimens from both Liriodendron and Magnolia in Massachusetts and found that the adults of both conformed to Forbes’ description of P. liriodendronella. A colleague of Eiseman also found just one species on Liriodendron and Magnolia. Based on these results, Eiseman (2019) suggested that P. magnoliella will eventually be synonymized with P. liriodendronella. Jim Petranka reared specimens from Liriodendron and Magnolia mines from Madison County that also were indistinguishable and conform to P. liriodendronella as described by Forbes (1923). However, larvae on Magnolia tended to pupate beneath curled leaf edges, while those on Liriodendron tended to pupate in folds of the leaf that were inward from the leaf edge. This behavioral difference suggest the possibility of two species. Until taxonomic issues are resolved, we have arbitrarily decided to treat leaf mines on Liriodendron as being those of P. liriodendronella, and leaf mines on magnolias to be those of P. magnoliella. Adults that were collected at sites that had Liriodendron, but no Magnolia, are also presumed to be P. liriodendronella. In cases where representatives of both host genera were present -- and the specimen possessed a golden streak that was edged with brown -- the specimen was assigned to the Phyllocnistis liriodendronella__magnoliella complex.
Identification
Field Guide Descriptions: Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIFTechnical Description, Adults: Forbes (1923); Eiseman (2019). Technical Description, Immature Stages: Eiseman (2019)                                                                                 
Adult Markings: Phyllocnistis liriodendronella and P. magnoliella that we have reared from different host plants in North Carolina are indistinguishable, and the following description applies to both species. The base color of the forewing is silvery white with golden yellowish patches and streaks on the apical third. About midway, there is a matching pair of oblique costal and dorsal streaks that converge near the middle to form either a complete and incomplete posteriorly angled fascia. The streaks are golden-yellow and have well-defined dark margins. A broad, golden-yellow longitudinal streak, often with less prominent dark margins on both sides, extends from the wing base to near the apex of the fascia. This streak may sometimes fused with the fascia. A smaller broad golden-yellow costal streak occurs just posterior to the apex of the fascia. This streak runs nearly perpendicular to the costa, has a faint dark margin on the posterior edge, and often extends to the apex of the fascia. Beyond this streak, there are three short subapical dark lines with surrounding golden-yellowish wash, and a conspicuous apical spot. The dark lines run roughly perpendicular to the costa and into the fringe. In addition to these, two or three rather poorly defined dark lines are often evident in the apical fringe, along with a dark line that begins at the apical spot and arches anteriorly. Phyllocnistis liriodendronella and P. magnoliella are the only species of Phyllocnistis in our area that have a longitudinal golden streak from the base to the middle of the forewing. These species are best separated by their host plants (see the note above concerning the taxonomic uncertainty of P. liriodendronella and P. magnoliella).
Wingspan: 6 mm (Forbes, 1923)
Immatures and Development: The larvae of Phyllocnistis are leafminers that typically have four instars. The first three are highly specialized sap-feeding stages. These lack both legs and eyes and create long serpentine mines. The final instar is a non-feeding stage that spins a cocoon in an enlarged chamber at the end of the mine. Adults of the final seasonal brood overwinter and become active the following spring. Phyllocnistis magnoliella produces a long, sinuous mine that often criss-crosses or repeatedly folds-back on itself. The larvae only mine the leaf epidermis and feed on the internal fluids of the cells, which produces a whitish track. The mine is essentially identical to that of Phyllocnistis liriodendronella, and has a well-defined narrow frass line that is usually evident near the middle of the otherwise whitish mine. The mines can be found on both expanding and fully formed leaves beginning with the spring leaf-out (Eiseman, 2019). Mines that we have observed on deciduous magnolias in the mountains were produced on the upper leaf surface, while mines observed on Sweetbay Magnolia at one site in the Coastal Plain were on the undersides of leaves. The larvae usually fold a small portion of the leaf margin to create a pupation chamber, although the pupal chambers are occasionally produced away from the leaf margin.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Scattered populations that are presumed to be P. magnoliella have been found throughout the eastern US. This species is fairly common at lower to mid-elevations in the mountains. Scattered populations occur elsewhere in the state, often in association with Magnolia virginiana.
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: Our records for occupied mines and adults are from June and July, which implies that there is only one brood per year.
Habitats and Life History
Habitats: This species mines the leaves of at least four species of native magnolias. It has been observed in the mountains primarily in forests with moist to well-drained soils, and typically with circumneutral or slightly acidic soils. A key is the presence of either Cucumber Magnolia or Fraser Magnolia on site. As of 2022, we have several records from the Coastal Plain where mines were found on Sweetbay Magnolia, a species that is associated with acidic wetlands.
Larval Host Plants: As of 2022, we have records of leaf mines on five of our six native magnolias: Cucumber Magnolia (M. acuminata), Fraser's Magnolia (M. fraseri), Southern Magnolia (M. grandiflora), Umbrella Magnolia (M. tripetala), and Sweetbay Magnolia (M. virginiana). The record for M. tripetala was for a planted (ornamental) tree in Madison Co. that was heavily infected with P. magnoliella.
Observation Methods: We recommend searching for the mines on leaves on native magnolias, and rearing and photographing the adults.
Wikipedia
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR SU
State Protection:
Comments:

 Photo Gallery for Phyllocnistis magnoliella - Magnolia Serpentine Leafminer Moth

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

Recorded by: Jim Petranka and Becky Elkin on 2022-08-09
Watauga Co.
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Recorded by: Jim Petranka and Becky Elkin on 2022-08-02
Jackson Co.
Comment: Unoccupied mines were on Magnolia acuminata.
Recorded by: Jim Petranka and Becky Elkin on 2022-07-20
Mitchell Co.
Comment: Unoccupied mines were on Magnolia acuminata.
Recorded by: Jim Petranka on 2022-07-15
Buncombe Co.
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Recorded by: Dean Furbish on 2022-07-11
Wake Co.
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Recorded by: Jim Petranka on 2022-06-23
Buncombe Co.
Comment: Occupied mines were on Magnolia fraseri.
Recorded by: Jim Petranka and Becky Elkin on 2022-02-08
Buncombe Co.
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Recorded by: David George and L. M. Carlson on 2021-12-15
Orange Co.
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Recorded by: Jim Petranka and Becky Elkin on 2021-10-19
Surry Co.
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Recorded by: Jim Petranka and Becky Elkin on 2021-10-19
Wilkes Co.
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Recorded by: Jim Petranka and Becky Elkin on 2021-09-09
Jackson Co.
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Recorded by: Jim Petranka, Becky Elkin and Bo Sullivan on 2021-08-02
Ashe Co.
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Recorded by: Jim Petranka, Becky Elkin and Bo Sullivan on 2021-08-02
Ashe Co.
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Recorded by: Jim Petranka and Becky Elkin on 2021-07-21
Graham Co.
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Recorded by: Jim Petranka and Becky Elkin on 2021-07-13
Burke Co.
Comment: Unoccupied mines were on Magnolia tripetala.
Recorded by: Jim Petranka and Becky Elkin on 2021-07-01
Buncombe Co.
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Recorded by: Jim Petranka and Becky Elkin on 2021-06-30
Mitchell Co.
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Recorded by: Jim Petranka and Becky Elkin on 2021-06-27
Buncombe Co.
Comment: Unoccupied mines were on Magnolia acuminata
Recorded by: Jim Petranka and Becky Elkin on 2021-06-27
McDowell Co.
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Recorded by: Jim Petranka on 2021-06-21
Buncombe Co.
Comment: Unoccupied mine was on M. acuminata.
Recorded by: Jim Petranka on 2021-06-15
Madison Co.
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Recorded by: Jim Petranka, Bo Sullivan and Steve Hall on 2021-05-10
Scotland Co.
Comment: Unoccupied mine was on M. virginiana.
Recorded by: Jim Petranka, Bo Sullivan and Steve Hall on 2021-05-10
Scotland Co.
Comment: Unoccupied mine was on M. virginiana.
Recorded by: Jim Petranka on 2021-03-29
Bladen Co.
Comment: Unoccupied mine was on M. virginiana.
Recorded by: Ken Kneidel on 2020-12-23
Mecklenburg Co.
Comment: Unoccupied mine on a Magnolia grandiflora leaf.
Recorded by: Ken Kneidel on 2020-12-23
Mecklenburg Co.
Comment: Unoccupied mine on a Magnolia grandiflora leaf.
Recorded by: Ken Kneidel on 2020-12-23
Mecklenburg Co.
Comment: Unoccupied mine on a Magnolia grandiflora leaf.
Recorded by: Jim Petranka on 2020-11-07
Buncombe Co.
Comment: An unoccupied mine was on Magnolia grandiflora.
Recorded by: Jim Petranka on 2020-09-15
Yancey Co.
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Recorded by: Jim Petranka on 2020-09-09
Madison Co.
Comment: Unoccupied mines were common on a planted Magnolia tripetala that was next to a woodland border.