Blues: Bauer’s dotted-blue (Euphilotes baueri)
(Lycaenidae: Polyommatinae: Scolitantidini)
Profile prepared by Mace Vaughan and Matthew Shepherd, The Xerces Society for Invertebrate Conservation
Bauer’s Dotted-blue has a very limited distribution: eastern California, central Nevada, and northwest Arizona. It may also occur in southwest Utah. Its habitat is dry slopes and desert flats with scattered short brush where the larval hostplants, various wild buckwheats, grow. The major threat is loss of habitat due to invasive alien plants, mainly cheatgrass (Bromus tectorum), which may out-compete buckwheat hostplants as well as increase fire risk.
Xerces Red List Status: Imperiled
Canada – Species at Risk Act: N/A
Canada – provincial status: N/A
USA – Endangered Species Act: None
USA – state status: None
IUCN Red List: N/A
Bauer’s Dotted-Blue is considered Imperiled because of its restricted range, rarity within that range, and the threat of habitat degradation due to invasive weeds. None of the four states in which Bauer’s Dotted-Blue occurs allows listing of insects under state statute.
Bauer’s Dotted-Blue is a small, delicately colored butterfly in the family Lycaenidae (gossamer-wings). The wingspan is between 19 mm and 22 mm (¾ to ? inch) Males are pale blue above. Females are gray-brown with blue scaling varying from extensive to almost none and the orange aurora band on outer edge of hindwing ranges from medium to absent. The underside of the wings on both genders are snowy white with a distinct black line on the wing margins, a narrow, pale orange marginal band, and bold black spotting typ ical of the dotted-blues.
Euphilotes baueri (Shields), 1975. Some authorities considered it a subspecies, Euphilotes battoides baueri, Bauer’s Square-Spotted Blue.
Habitat is dry slopes and desert flats with scattered short brush. The larval hostplants are wild buckwheats—Kennedy’s (Eriogonum kennedyi), oval- leafed (or cushion) (E. ovalifolium), and strict (or Blue Mountain) buckwheat (E. strictum). There is a single flight period from mid-April to late June. Males patrol all day near hostplants to find receptive females. Adults drink nectar, particularly from buckwheat. Eggs are laid singly on hostplant flowers. Caterpillars eat flowers and seeds of hostplants and are tended by ants. Chrysalids hibernate in sand or leaf litter.
Bauer’s Dotted-Blue has a very limited distribution: eastern California, central Nevada, and northwest Arizona. It may also occur in southwest Utah.
The major threat is loss of habitat due to invasive alien plants, mainly cheatgrass (Bromus tectorum). Cheatgrass may out-compete buckwheat hostplants as well as increase fire risk in the habitat.
Habitats should be surveyed to assess impact of invasive weeds and management actions taken to control weeds, if necessary, to maintain hostplant populations.
Surveys for new populations and monitoring to assess status of known populations are valuable. Studies to evaluate the threat posed by invasive weeds and the butterfly’s susceptibility to them would be useful.
Emmel, T.C. (Editor). 1998. Systematics of Western North American Butterflies. Mariposa Press, Gainesville, FA.
Opler, P.A. 1999. A Field Guide to Western Butterflies. Houghton-Mifflin Co., Boston, MA.
Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, CA.
Stanford, R. E., and P. A. Opler. 1993. Atlas of Western USA Butterflies Including Adjacent Parts of Canada and Mexico. Denver and Fort Collins, CO.
Arizona Game and Fish; Invertebrate Abstracts, Distribution Maps, and Illustrations: Euphilotes baueri (Accessed 5/9/05)
Big Sky Institute, Butterflies and Moths of North America: Bauer’s Dotted-Blue (Accessed 1/14/09)
NatureServe Explorer (Accessed 5/9/05)
Vaughan, D. M., and M. D. Shepherd. 2005. Species Profile: Euphilotes baueri. In Shepherd, M. D., D. M. Vaughan, and S. H. Black (Eds). Red List of Pollinator Insects of North America. CD-ROM Version 1 (May 2005). Portland, OR: The Xerces Society for Invertebrate Conservation.