Moths of North Carolina
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Bucculatrix Members:
4 NC Records

Bucculatrix canadensisella Chambers, 1875 - Birch Skeletonizer Moth

Superfamily: Gracillarioidea Family: BucculatricidaeSubfamily: [Bucculatriginae]Tribe: [Bucculatrigini]P3 Number: 330080.00 MONA Number: 560.00
Comments: Bucculatrix is a large genus of small leaf-mining moths, with around 300 species worldwide. A total of 103 Nearctic species have been described, and many others will likely be described in the future. Braun (1963) covered 99 species in her monograph, and four additional Nearctic species have been described since then.
Species Status: Friend (1927) has a very comprehensive treatment of the life history and ecology of this species.
Field Guide Descriptions: Covell (1984)Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Braun (1963, p. 147)Technical Description, Immature Stages: Braun (1963)                                                                                 
Adult Markings: This is a minute, dark brown and white streaked moth. The following description is based on that by Braun (1963). An even more detailed description is in Friend (1927). The face is whitish to grayish brown, and the tuft white with a brown center. A broad zone of white is present below the tufts and thorax due to white coloration on the head, tegula, and the base of the forewing. The eyecap is white, and the antennal stalk has narrow brown annulations. The ground color of the forewing and thorax is dark brown to reddish brown. There are three posteriorly oblique white streaks that extend from the costa to the middle of the wing. One begins at one-fifth the wing length, the second at the middle, and the third at about three-fourths. The inner margin has a short, white, posteriorly oblique streak just before the middle that nearly meets the apex of the first costal streak. A patch of black raised scales borders the streak posteriorly. A second and less oblique dorsal streak occur at the tornus and is slightly anterior to the third costal streak. The wing tip has a black apical spot that is partially or completely surrounded by white scales. The fringe is reddish brown with a faint, irregular line of dark-tipped scales that extends from above the black spot to the tornus. The hindwing is gray, and the cilia brownish or reddish tinged. The legs are brown outwardly, with the tarsal segments broadly brown-tipped. The general patterning of Bucculatrix canadensisella is similar to that of B. coronatella. It can be distinguished based on its much darker ground color, and the broad zone of whitish wash below the tufts and thorax.
Wingspan: 7-8.5 mm (Braun, 1963)
Adult Structural Features: The male and female genitalia, along with associated scale tufts and patches, are distinctive and are described and illustrated by Braun (1963). The following are her verbatim descriptions. Males: harpes typical of the section, setose outwardly, terminating at apex in a small pointed process, a small basal process; socii short, broad, setose, sinus between them shallow; aedeagus stout, tapering to the acutely pointed tip; vinculum a very narrow sclerotized band. Scales of scale sac of two kinds, slender and pointed and broadly oval. Females: both dorsal and ventral posterior margins of segment 7 fringed with long specialized scales; on the intersegmental membrane and ventral to ostium, a dense tuft of specialized scales on each side of mid-ventral line; on sternite of segment 8, on each side of ostium, a large dense patch composed of several rows of specialized scales; on anterior margin of tergite of 8, a row of very small scales, emarginate mid-dorsally; margin of ostium sclerotized, with two outwardly directed acute processes; signum ribs with long spines posteriorly, grading anteriorly to short acute spines.
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The females lay eggs on either side of the leaf. The mine is initially highly convoluted and resembles a blotch. After about a week, the larva then lengthens the mine rapidly to produce a very narrow track. The completed mine is about 15-20 mm long (Friend, 1927; Braun, 1963). The larva eventually emerges from the mine at the end of the third instar by cutting a crescentic opening in the lower epidermis. It immediately molts beneath a white webbing (molting cocoon). The last two instars feed externally and skeletonize the leaves in patches. Feeding normally takes place on the underside of the leaf and the upper epidermis is left intact. The final instar larvae are about 6 mm long, yellowish green with a brown head, and whitish tubercles. When ready to spin the cocoon, the larva drops to the ground using a long silt thread and pupates in a ribbed cocoon on the underside of surface debris. The pupa is spindle-shaped, about three mm long and brown (Friend, 1927). Overwintering occurs in the pupal stage, and the adults emerge the following summer. Bucculatrix canadensisella often has regional population irruptions at northern latitudes and can be a significant defoliating pest. There are often numerous mines on a single leaf, in some cases up to 25 to 40 mines per leaf (Friend, 1927).

Distribution in North Carolina
Distribution: Bucculatrix canadensisella is mostly found at northern latitudes in North America. It is widespread in Canada, occurring from British Columbia to Newfoundland. In the US, it occurs from Maine and adjoining states westward to Minnesota, and southward mostly along the Appalachians to as far south as eastern Tennessee and western North Carolina. There is one disjunct population in Colorado (Braun, 1963). As of 2021, all of our records are from higher elevation sites in the Blue Ridge. Braun (1963) collected specimens at Eagle's Nest, which we believe corresponds to a site in Avery County. She also mentions a record from the Tennessee side of New Found Gap in the Great Smoky Mountains, suggesting that it may be found throughout the Blue Ridge, at least at high elevations.
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: Local populations appear to be univoltine (Friend, 1927), with adults active from May through August in areas outside of North Carolina. As of 2021, our records are from June and July.
Habitats and Life History
Habitats: Records from North Carolina, as well as records from Tennessee and Kentucky, come from elevations above 4,000 ft. The host plants in those areas were Yellow Birch in stands of northern hardwoods (Shafale and Weakley, 1990).
Larval Host Plants: The larvae specialize on birches (Braun, 1963; Eiseman, 2019). The known hosts include European White Birch (Betula pubescens), Yellow Birch (Betula alleghaniensis), Sweet Birch (B. lenta), River Birch (B. nigra), Water Birch (B. occidentalis), Gray Birch (B. populifolia) and Paper Birch (B. papyrifera). There are two records of larvae using B. alleghaniensis in the southern Appalachians (Braun, 1963), including one from North Carolina. - View
Observation Methods: The adults are attracted to lights. Friend (1927) noted that the adults often rest on ground vegetation such as ferns during the day and can be easily collected by sweep-netting. They make daily migrations into birch trees to mate. We recommend searching for the mines on birch leaves to better document host use and habitat requirements for North Carolina populations.
See also Habitat Account for General Montane Mesic Forests
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR [SU]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: Based on the few records collected so far, this species appears to be associated with high elevation stands of Northern Hardwoods, where it may be one of a number of Pleistocene relicts that persist in our mountains. If so, then it may be significantly threatened by reduction in cool moist forests due to the effects of global climate change. However, much more information is needed on its distribution, host plants, and habitat preferences in North Carolina before any conclusions can be reached about its conservation status.

 Photo Gallery for Bucculatrix canadensisella - Birch Skeletonizer Moth

Photos: 4

Recorded by: Jim Petranka and Becky Elkin on 2019-07-25
Madison Co.
Recorded by: Jim Petranka and Becky Elkin on 2019-07-25
Madison Co.
Recorded by: B. Bockhahn, K. Kittelberger, P. Scharf on 2015-06-18
Avery Co.
Recorded by: Kyle Kittelberger, Brian Bockhahn, Paul Scharf on 2014-06-10
Mitchell Co.