Moths of North Carolina

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View PDF	Yponomeutidae Members:	Swammerdamia Members:	22 NC Records

Swammerdamia caesiella (Hübner, 1796) - Gray-blue Swammerdamia

Taxonomy

Superfamily:
Yponomeutoidea

Family:
Yponomeutidae

Subfamily:
Yponomeutinae

Tribe:
[Yponomeutinae]

P3 Number:
36a0115

MONA Number:
2413.00

Other Common Name:
Birch Ermel

Comments: Swammerdamia caesiella in North America are very similar to European forms that are nearly identical in adult and larval maculation, but the two are genetically different and fall into separate BINS (BOLD). Here, we limit this species to North American populations.

Identification

Field Guide Descriptions: Beadle and Leckie (2012)

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

Technical Description, Adults: Duckworth (1965)

Adult Markings: Swammerdamia caesiella is recognized by its bright white head and thorax that contrast with the bluish-gray forewings. The following description is based in part on that of Duckworth (1965). The labial palp is relatively short, weakly upcurved, and fuscous, with the apical tip white. The antenna has a white base, but is otherwise fuscous with white annulations. The head, face and thorax are all white, while the legs are light to dark gray, with the tarsi more or less annulated with dull white. The forewing is bluish-gray due to a mix of bluish-white and fuscous scales. Some specimens can have a small whitish costal spot just before the apex. The fringe is fuscous with a coppery luster, and the hindwing varies from gray to light brown with a concolorous fringe.

Wingspan: 9-13 mm (Duckworth, 1965).

Adult Structural Features: Duckworth (1965) has descriptions and illustrations of the male and female genitalia. Also, see below for specimens from North Carolina.

Genitalia and other structural photos

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

Immatures and Development: The larvae window-feed beneath a light webbing on the upper surfaces of leaves (Eiseman, 2022), but details of the life history are lacking. The later-instars are yellowish-green with three darker-green longitudinal stripes on the abdomen. The head and prothoracic shield are light amber-colored, with a conspicuous row of six dark spots (pinicula) on the anterior margin of the prothoracic shield (BugGuide; iNaturalist). The pinacula on the abdomen are surrounded by a zone of yellowish scales. The larvae pupate beneath their loose webbing in a tough, whitish cocoon that is often constructed in a leaf fold. Overwintering occurs in the pupal stage, with the adults emerging after the spring leaf-out.

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

Distribution in North Carolina

Distribution: Swammerdamia caesiella is most commonly found in eastern North America in areas with cool climates, but there are also scattered records from Alaska, the Yukon Territories, British Columbia, Alberta, Saskatchewan and Manitoba. In the East the range includes much of southern Canada from Ontario eastward to Nova Scotia, and portions of the US from Maine and other New England states westward through the Great Lakes region to Wisconsin and Minnesota, and southward to Illinois, Indiana, Ohio, West Virginia, eastern Kentucky, western Virginia, eastern Tennessee and western North Carolina. Scattered records are also known from western Tennessee, Arkansas, northern Georgia and northern Alabama. As of 2025, most of our records are from the Blue Ridge where it occurs from the lower valleys to as high as Mt. Mitchell. There also are two isolated records from the 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: The adults have been found from March through September in different areas of the range, with the peak season from May through August. As of 2025, our records extend from late-April through mid-August, with local populations at lower elevations in the Blue Ridge probably producing two broods annually.

Habitats and Life History

Habitats: Local populations in North Carolina are generally associated with hardwood forests, including semi-wooded residential neighborhoods.

Larval Host Plants: The host plants are somewhat nebulous due perhaps to taxonomic issues over the years. Eiseman (2022) listed alder (Alnus), birch (Betula), and chestnut (Castanea), while Duckworth (1965) listed birch, hawthorn (Crataegus) and cherry (Prunus) that were presumably based on museum labels. Birches appear to be the primary hosts, with Paper Birch (Betula papyrifera; BugGuide) often used in the northern part of the range. As of 2025, we do not have any rearing records for North Carolina. - View

Observation Methods: The adults are attracted to lights.

Wikipedia

Status in North Carolina

Natural Heritage Program Status:

Natural Heritage Program Ranks: GNR [S3]

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

Comments:

Photo Gallery for Swammerdamia caesiella - Gray-blue Swammerdamia

Photos: 22

	Recorded by: Jim Petranka on 2024-07-14 Madison Co. Comment:		Recorded by: Jeff Niznik on 2024-07-12 Watauga Co. Comment:
	Recorded by: Jim Petranka and Bo Sullivan on 2023-08-08 Ashe Co. Comment:		Recorded by: David George, Stephen Dunn, Jeff Niznik, Rich Teper, Becky Watkins on 2023-07-30 Swain Co. Comment:
	Recorded by: Jim Petranka on 2023-05-09 Madison Co. Comment:		Recorded by: Jim Petranka and Becky Elkin on 2022-08-14 Madison Co. Comment:
	Recorded by: tom ward on 2022-06-06 Buncombe Co. Comment:		Recorded by: Rob Van Epps on 2022-05-29 Mecklenburg Co. Comment:
	Recorded by: Rob Van Epps on 2022-05-29 Mecklenburg Co. Comment:		Recorded by: tom ward on 2022-05-08 Buncombe Co. Comment:
	Recorded by: tom ward on 2022-04-22 Buncombe Co. Comment:		Recorded by: Jim Petranka and Bo Sullivan on 2021-08-02 Ashe Co. Comment:
	Recorded by: tom ward on 2021-07-17 Buncombe Co. Comment:		Recorded by: Jim Petranka and Becky Elkin on 2021-05-21 Madison Co. Comment:
	Recorded by: Jim Petranka and Becky Elkin on 2020-06-09 Madison Co. Comment:	iNaturalist	Recorded by: megan186 - Megan Blythe on 2019-07-31 Macon Co. Comment: iNat record - https://www.inaturalist.org/observations/30014003***(c) Megan Blythe, some rights reserved (CC BY-NC-ND)\| Public Positional Accuracy=324 m Elevation=3508.4 feet
	Recorded by: Jim Petranka and Becky Elkin on 2019-07-20 Madison Co. Comment:		Recorded by: Jim Petranka and Becky Elkin on 2019-07-20 Madison Co. Comment:
	Recorded by: Steve Hall on 2019-05-29 Orange Co. Comment:		Recorded by: Steve Hall on 2019-05-21 Orange Co. Comment:
iNaturalist	Recorded by: loriannkayaker - Lori A Owenby on 2016-06-29 Yancey Co. Comment: iNat record - https://www.inaturalist.org/observations/3629100***(c) Lori A Owenby, some rights reserved (CC BY-NC)\| Public Positional Accuracy=13 m Elevation=6090.8 feet		Recorded by: B. Bockhahn, K. Kittelberger, P. Scharf on 2015-06-18 Avery Co. Comment:

Photos of Swammerdamia caesiella from iNaturalist
© loriannkayaker - Lori A Owenby - 2016-06-29 - Yancey Co. iNat record	© megan186 - Megan Blythe - 2019-07-31 - Macon Co. iNat record

Swammerdamia caesiella (Hübner, 1796) - Gray-blue Swammerdamia

Photo Gallery for Swammerdamia caesiella - Gray-blue Swammerdamia

Photos of Swammerdamia caesiella from iNaturalist