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Species Satyrium fuliginosum - Western Sooty Hairstreak - Hodges#4277

A Boisduval's Blue (Plebejus icarioides) ? - Satyrium fuliginosum - female Sooty Hairstreak - Satyrium fuliginosum Mating Sooty Hairstreaks - Satyrium fuliginosum - male - female Sooty Hairstreak - Satyrium fuliginosum
Show images of: caterpillars · adults · both
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Papilionoidea (Butterflies and Skippers)
Family Lycaenidae (Blues, Coppers, Hairstreaks, Harvesters)
Subfamily Theclinae (Hairstreaks)
Tribe Eumaeini
Genus Satyrium
Species fuliginosum (Western Sooty Hairstreak - Hodges#4277)
Hodges Number
Other Common Names
Sooty Hairstreak
Synonyms and other taxonomic changes
Lycaena fuliginosa W.H. Edwards, 1861. Type locality: Norden, El Dorado County, California
Lycaena suasa Boisduval, 1869. Type locality: Gold Lake, Sierra County, California
Satyrium fuliginosum tildeni Mattoon & Austin, 1998. Type locality: Siskiyou Mountains, Siskiyou County, California
Satyrium fuliginosum albolineatum Mattoon & Austin, 1998. Type locality: Boardman Ridge, North Coast Range, Lake Co., CA
Satyrium fuliginosum (W.H. Edwards)
Explanation of Names
Latin for "sooty"
Tailless, dorsal drab gray, underwing grayish to brown, with the FW usually having a line of dark dots circled in white, and the HW can have some whitish dots.

Distinction from S. semiluna as a distinct species from S. fuliginosa is debated, and needs further study in potential areas of contact. S. semiluna is distinguished by the presence (sometimes faint) of a "stigma" or "sex brand" on the upper front wing of the males (lacking in S. fuliginosum ), and by distribution. Zone of contact should be near the east base of the Sierra Nevada and northward across southwestern Oregon.

Similar species of Blues in genus Plebejus will usually show at least some blue scaling above, even in females (none in Sooty Hairstreaks); they will have a white fringe (dull grayish in Sooty Hairstreaks); and, the front wing will have a very strong black bar at the end of the discal cell (often there is a second black spot in the middle of the cell as well), while this spot is absent to weak and usually not black in Sooty Hairstreaks. The pattern of the lower side will usually have a "smoother" look in Blues, and will look dirty or "sooty" in the Hairstreaks. Also, the Sooty Hairstreaks will most often have the dark postmedian spots dull in color (sometimes only faint), while in the Blues they are usually bold and black. Fresh individuals are much easier to identify than faded worn specimens.
Sierra Nevada of California north in mountains through northern California into southern Oregon (west of Great Basin). Some populations further north in the Cascades show similarities to S. fuliginosum, but are classed as S. semiluna when the two are split as separate species.
Open, usually exposed areas in association with Lupines (Lupinus species).
One brood flies late June - August.
Larva feed on Lupines.
Print References
(1) (2)
Internet References