Moths of North Carolina
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View PDFGracillariidae Members: 7 NC Records

Micrurapteryx salicifoliella (Chambers, 1872) - Willow Leafblotch Miner Moth



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Taxonomy
Superfamily: Gracillarioidea Family: GracillariidaeSubfamily: GracillariinaeTribe: [Gracillariini]P3 Number: 330172.00 MONA Number: 647.00
Comments: The genus Micrurapteryx contains 12 recognized species that are all restricted to the Holarctic Region. Most occurring in the Palearctic Region and only two in North America. The larvae mine the leaves of legumes and willows.
Identification
Field Guide Descriptions: Covell (1984); Beadle and Leckie (2012)Online Photographs: MPG; BugGuide; BAMONATechnical Description, Adults: Chambers (1872); Forbes (1923).Technical Description, Immature Stages: Eiseman (2019); Furniss et al. (2001)                                                                                 
Adult Markings: The following is primarily based on descriptions in Chambers (1872) and Forbes (1923). The face is white and the maxillary palp blackish. The labial palp is white with the second joint mostly suffused with black, and the third joint with black rings at the base, middle, and apex. The vertex is mostly white, but suffused with brown in the front, and with a blackish patch at the base of the dark brown antennae. The thorax and dorsal portion of the forewing is white, while the costal portion is blackish brown. The line of demarcation between the white dorsal portion and dark costal portion is scalloped, with three or four bulges. There are usually five white costal streaks or strigulae. The first is a long thin streak that begins on the costa at about one-fourth and curves posteriorly towards the inner margin. The second often begins confluent with the first and extends along the costa a short distance before broadening near its terminus. This is followed by three short strigulae that tend to converge towards a common point near the middle of the wing. Individuals are variable, and some may lack one or more of the streaks or strigulae. There is a rather indistinct brown apical spot at the base of the cilia. The cilia are whitish with a well defined dark marginal line at the base. A second dark line is often evident just below the apex of the cilia, and there are usually two extended dark fingers of fringe that produce tail-like features. The legs have black and white barring. Micrurapteryx occulta closely resembles M. salicifoliella, but tends to have more white strigulae along the costal margin that are more pronounced. These species also differ in their mine morphology and host plants (legumes versus willows).
Wingspan: 9-10 mm (MPG; Forbes, 1923).
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The eggs are laid singly on the undersides of leaves. The first three instars produce narrow, whitish epidermal mines on the lower leaf surface, with liquid frass deposited in a central line. Fourth and fifth instars tunnel deeper into the tissues where they create conspicuous greenish blotches on the upper leaf surface. These eventually become necrotic and turn reddish brown or brown. Smaller mines are lobed in outline, but adjoining mines of multiple larvae often coalesce and cover the entire leaf surface (Eiseman, 2019; Furniss et al., 2001). Frass is expelled through crescent-shaped slits in the lower epidermis. The final instar larvae leave the mines and spin flat, oval-shaped cocoons that are usually on the upper leaf surface, but sometimes below. The cocoons have a bulging, cellophane-like appearance, with a ring of denser silk around the margin. The upper surface is decorated with numerous opaque white flecks (Eiseman, 2019). The adults overwinter and become active with the spring warm-up.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Micrurapteryx salicifoliella is broadly distributed across North America from Alaska to Quebec. In the eastern US, it occurs in the northeastern states southwestward to at least Tennessee and North Carolina. In the West, populations occur as far south as California and Arizona.
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: Populations appear to be univoltine at northern latitudes, and possibly bivoltine farther south. In Alaska, oviposition occurs in late May and the adults emerge in late July and August. The phenology is similar in Illinois, but with adults of a possible second generation emerging in October (Eiseman, 2019). As of 2020, we have records of leaf mines and a reared adult that extend from July through mid-September.
Habitats and Life History
Habitats: This species requires willows as hosts, which are found in a variety of moist to wet habitats that are not heavily shaded. Silky Willow and Black Willow appear to be the most important hosts in North Carolina. Look for these in open, sunny habitats such as wet ditches, and along the margins of streams, ponds, and marshes.
Larval Host Plants: The larvae feed on willows, including at least 16 species of native and introduced species (Furniss et al., 2001; Eiseman, 2019). Several of the known hosts occur in North Carolina, including White Willow (Salix alba), Weeping Willow (S. babylonica), Black Willow (S. nigra) and Silky Willow (S. sericea). As of 2020, we have mine records from S. sericea in the mountains and S. nigra in the Piedmont and Coastal Plain.
Observation Methods: The adults occasionally visit lights and the mines are conspicuous on willow leaves.
Wikipedia
See also Habitat Account for Shoreline Shrublands
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: G5 SU
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: As of 2020, we have only a few scattered records for this species in the state, where it appears to be near the limit of its southern range in the eastern US. Additional information on the distribution and abundance of this species is needed before we can assess its conservation status.

 Photo Gallery for Micrurapteryx salicifoliella - Willow Leafblotch Miner Moth

Photos: 8

Recorded by: Jim Petranka, John Petranka, Becky Elkin, and Steve Hall on 2021-09-28
Durham Co.
Comment:
Recorded by: Jim Petranka, John Petranka, Becky Elkin, and Steve Hall on 2021-09-28
Durham Co.
Comment:
Recorded by: Jim Petranka on 2020-09-14
Madison Co.
Comment: An adult that was reared from a mine on Silky Willow (see companion photos of the mine from 2020-08-25).
Recorded by: Jim Petranka on 2020-09-14
Madison Co.
Comment: An adult that was reared from a mine on Silky Willow (see companion photos of the mine from 2020-08-25).
Recorded by: Jim Petranka on 2020-08-25
Madison Co.
Comment: A view of the upper surface of a leaf of Silky Willow (Salix sericea) with two late-instar mines (see companion photo of the lower-surface mines).
Recorded by: Jim Petranka on 2020-08-25
Madison Co.
Comment: A view of the lower surface of a leaf of Silky Willow (Salix sericea) with two early-instar epidermal mines. As larvae mature they begin feeding on internal tissues and produce flat, upper-surface mines (see companion photo of the upper-surface mines.
Recorded by: Jim Petranka on 2020-08-25
Madison Co.
Comment: A feeding late-instar larva on Silky Willow (Salix sericea).
Recorded by: Jim Petranka on 2020-08-25
Madison Co.
Comment: A larva from a mine collected on 2020-08-25 evacuated the mine and spun a cocoon on 2020-08-30 (see companion photo of the mine).