See the discussion under Western Tailed Blue. The Eastern and Western tailed blues can be reliably distinguished only by examination of male genitalia.
Immature Stages
The immatures are very similar to those of the Western Tailed Blue (Scudder 1889b). Lawrence and Downey (1967) described the immature stages in extreme detail.
Subspecies
BC populations are the nominate subspecies, E.c. comyntas, which occurs everywhere except the southern extreme of the species range (TL: "North America").
Genus Description
The origin of the name Everes is unknown (Emmet 1991). The common name "tailed blues" refers to the adults having small tails on the hindwings, which is unusual in temperate species of blues. Scudder (1875) first used the name "tailed blue" for the Eastern Tailed Blue.
This is the only genus of blues in BC with tails on the hindwings.lt is also the only genus of blues with a well-developed uncus in the male genitalia. The eyes are smooth and the palpi are porrect and twice as long as the head. The genus is Holarctic, with a total of five species, two of which are found in the Nearctic and BC. The larvae of all species in the genus feed on perennial Fabaceae.
There are two very similar species of tailed blues in BC. Where the two species distributions overlaps, the species can be differentiated only by examination of the male genitalia.
Biology
The few records of the Eastern Tailed Blue in BC indicate that there is one generation from mid-June to mid-July. Nothing is known of the life cycle of any of the western disjunct populations of this species, but the life cycle of eastern populations has been well described by various vorkers (Scudder 1889b). This species has the same habits as the Western Tailed Blue. The eastern larval foodplant, Lespedeza capitata, is not found in BC, but Lawrence and Downey (1967) record white clover (Trifolium repens) and red clover (T. pratense), which do occur in BC. The ability to utilize these weedy clovers that have spread throughout the west may account for the recently discovered British Columbia populations.
Habitat
The Eastern Tailed Blue is known from only three populations in BC, one in the Flathead drainage, one near Vernon, and another near the mouth of the Pend-d'Oreille River, south of Trail. There are also scattered records in adjacent eastern Washington and the Idaho panhandle. Washington and Oregon authorities (pers. comm.) have speculated that the species was brought in by nursery stock. BC populations, however, are found in natural riparian situations with, in the case of the Flathead population, little or no human disturbance. This would indicate that the species is native to the Pacific Northwest. The isolated populations most likely represent remnants of a much larger preglacial or immediate postglaciaI distribution, similar to the distribution of the Dione Copper in the upper Columbia River drainage.
Distribution
Distribution
The Eastern Tailed Blue is found as disjunct populations from the Willamette Valley, OR, south to central CA, the upper Columbia River drainage of WA, BC, and ID, and then from MB and CO east and south to TX and FL, with other populations in AZ/NM south into northern MEX.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2025-04-27 7:59:31 PM]
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