Moths of North Carolina

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View PDF	Gracillariidae Members:	Parectopa Members:	102 NC Records

Parectopa robiniella Clemens, 1863 - Locust Digitate Leafminer Moth

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Taxonomy

Superfamily:
Gracillarioidea

Family:
Gracillariidae

Subfamily:
Gracillariinae

Tribe:
[Gracillariini]

P3 Number:
33a0118

MONA Number:
657.00

Comments: The genus Parectopa contains around 40 species that are found worldwide, including nine species in North America. All are very small moths that are specialized leafminers.

Species Status: Parectopa robiniella is native to the eastern US and adjoining areas of southern Canada, but its range has expanded in North America with the planting and spread of its primary host (Black Locust; Robinia pseudoacacia) outside of its natural range. Parectopa robiniella became established in northern Italy around 1970 and subsequently spread to many regions of Europe. In Europe it feeds entirely on Black Locust, which is widely planted as an ornamental, and as a source of wood for heating, fencing, furniture and general construction (Hulujan et al., 2017). Due to a lack of natural control agents, P. robiniella can cause major defoliation of trees in Europe. In North America native parasitoids keep populations of P. robiniella in check and the host plants rarely suffer significant damage.

Identification

Field Guide Descriptions: Beadle and Leckie (2012); Leckie and Beadle (2018).

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

Technical Description, Adults: (Eiseman 2019)

Technical Description, Immature Stages: Weaver and Dorsey (1967); Eiseman (2019).

Adult Markings: Adults have a dark brown head that is topped with elongated, white scale tufts. The forewings are dark brown with three oblique silvery costal streaks that alternate with three dorsal oval blotches or streaks. Near the tip of the wing, a transverse, curved silvery line passes from the costa to the tornus. There are also two converging dark brown to black lines at the base of the cilia that do not meet (Eiseman 2019). P. lespedezaefoliella is similar, but the curved silvery line is either absent or greatly reduced, and the two dark lines at the base of the cilia touch (or nearly touch) one another. This species is most easily documented by searching for the distinctive digitate blotch mines on Black Locust (Robinia pseudoacacia) or other legumes that serve as host plants.

Wingspan: 7-8 mm.

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

Immatures and Development: Females deposit eggs on the lower leaf surfaces, typically basally near the midrib or a larger vein. A hatchling initially makes a linear underside mine, then expands this to form a triangular, whitish blister. As the larva develops, it switches to mining the upper surface and eventually expands the mine to produce a distinctive digitate blotch mine that is normally centered on the midrib. The mine is initially pale green, but turns yellowish brown with age. Frass is either deposited in the lower surface mine or outside of the upper mine, so that the digitate blotch mine appears clean (Eiseman 2019). The late instar larvae are light green and pupation occurs in a flat, white cocoon that is spun outside of the mine.

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

Distribution in North Carolina

Distribution: Parectopa robiniella is native to eastern North America. Populations occur in southern Canada (Ontario; Quebec; Nova Scotia) and throughout much of the eastern US to as far south as Florida and the Gulf Coast. In North Carolina, P. robiniella occurs throughout much of the lower to upper-elevations of the Blue Ridge, as well as in the Piedmont and western Coastal Plain. Populations are restricted to sites where Black Locust or other host plants occurs locally. Records from iNaturalist include Stokes and Scotland counties.

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

Habitats and Life History

Habitats: This species is often found in open woodlands and along roadways with Black Locust and other legumes that are host species.

Larval Host Plants: Black Locust (Robinia pseudoacacia) appears to be the primary host plant, but the digitate leaf mines can be found on other legumes, including species of Amorpha, Desmodium, Galactia, and Lespedeza (Eiseman 2019). In North Carolina, we also have records of the species using American Groundnut (Apios americana), Bristly Locust (R. hispida), Dwarf Locust (R. nana), Shrub Lespedeza (Lespedeza bicolor), a Desmodium, and Smooth Milkpea (Galactia volubilis). - View

Observation Methods: This species can be easily detected by searching for the conspicuous leaf mines on Black Locust and other host plants.

Wikipedia

See also Habitat Account for Locust Groves and Thickets

Status in North Carolina

Natural Heritage Program Status:

Natural Heritage Program Ranks: GNR S4

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

Comments: Populations are common in the Blue Ridge and western Piedmont, but more spotty further east. Overall, the species appears to be secure in the mountains; the status elsewhere is less certain.

Photo Gallery for Parectopa robiniella - Locust Digitate Leafminer Moth

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

	Recorded by: Jim Petranka, Marilyn Westphal and Becky Elkin on 2025-08-18 Henderson Co. Comment: Occupied mines were on Black Locust.		Recorded by: Jim Petranka, Marilyn Westphal and Becky Elkin on 2025-08-18 Henderson Co. Comment: Occupied mines were on Black Locust.
	Recorded by: David George, Kevin Bischof, Rich Teper, Patrick Coin on 2025-08-16 Transylvania Co. Comment:		Recorded by: Mark Basinger on 2025-08-14 Ashe Co. Comment:
	Recorded by: Mark Basinger, Jim Petranka, and Becky Elkin on 2025-08-03 Moore Co. Comment:		Recorded by: Mark Basinger, Jim Petranka, and Becky Elkin on 2025-08-03 Moore Co. Comment:
	Recorded by: Mark Basinger on 2025-08-01 Rowan Co. Comment:		Recorded by: Mark Basinger on 2025-07-24 New Hanover Co. Comment:
	Recorded by: Mark Basinger on 2025-07-14 Richmond Co. Comment:		Recorded by: Mark Basinger on 2025-07-14 Scotland Co. Comment:
	Recorded by: Mark Basinger on 2025-07-10 Bladen Co. Comment:		Recorded by: Jim Petranka, Mark Basinger and Becky Elkin on 2025-06-28 Moore Co. Comment:
	Recorded by: Mark Basinger, Jim Petranka, and Becky Elkin on 2025-06-26 Mitchell Co. Comment:		Recorded by: Mark Basinger on 2025-06-22 Buncombe Co. Comment:
	Recorded by: Mark Basinger on 2025-06-05 Wilson Co. Comment:		Recorded by: Jim Petranka, Becky Elkin, Tracy Feldman, David George, Jeff Niznik and John Petranka. on 2025-05-09 Cumberland Co. Comment:
	Recorded by: Tracy Feldman, David George on 2025-05-09 Cumberland Co. Comment:		Recorded by: Mark Basinger on 2024-10-17 Davidson Co. Comment:
	Recorded by: Mark Basinger on 2024-10-17 Montgomery Co. Comment:		Recorded by: Mark Basinger on 2024-10-17 Stanly Co. Comment:
	Recorded by: Mark Basinger on 2024-09-19 Buncombe Co. Comment:		Recorded by: Mark Basinger on 2024-09-06 Wilson Co. Comment:
	Recorded by: Mark Basinger on 2024-09-06 Wilson Co. Comment:		Recorded by: Mark Basinger and Donald Zepp on 2024-08-23 Nash Co. Comment:
	Recorded by: Mark Basinger on 2024-08-09 Mitchell Co. Comment:		Recorded by: Jim Petranka on 2024-07-19 Madison Co. Comment:
	Recorded by: Ken Kneidel on 2024-06-28 Mecklenburg Co. Comment:		Recorded by: Ken Kneidel on 2023-10-14 Burke Co. Comment:
	Recorded by: R. Newman on 2023-09-28 Carteret Co. Comment: Mine was on Galactia volubilis.		Recorded by: David George, Stephen Dunn, Jeff Niznik on 2023-07-31 Macon Co. Comment: