Xerces Blue Butterfly
by: Robert C. Kuhmann
"Each extinction is a unique voice silenced in a universal conversation,
of which we ourselves are only one participant."
1875, San Francisco lepidopterist Herman Behr wrote to his Chicago
colleague Herman Strecker, lamenting that the Xerces Blue butterfly was
"now extinct (as regards the neighborhood of San Francisco). The
locality where it used to be found is converted into building lots, and between
German chickens and Irish hogs no insect can exist besides louse and flea.
" Eventually, Behrís prophecy panned out, and the Xerces Blue
ceased flying altogether.
The Xerces Blue butterfly (Glaucopsyche
lygdamus xerces) is perhaps the most famous of the extinct
United States butterflies. It was a fascinating species that was once
locally common at suitable habitats on the San Francisco Peninsula. It
was of great interest to lepidopterists due to the remarkable variation
in wing pattern; indeed, some of these varieties were originally
considered to represent distinct species, until it was observed that the
various forms readily interbred. The Xerces Blue, in essence, was a
sub-species which consisted of only one population, although great
variation was present in the individuals comprising the population. From
this standpoint alone, the butterfly would have made an excellent
subject for genetic, evolutionary, and ecological studies. Xerces was a
small butterfly, the upper wing surfaces iridescent blue-violet in the
male, brown in the female. Populations inhabited stabilized sandy sites
with rather low-growing vegetation, including the former Lone Mountain
Cemetery, the Presidio military base (just west of the Naval Hospital
and north of Lobos Creek), several locations in the Sunset District
(including the western slopes of Twin Peaks), and the Lake Merced area.
By the 1930's, the butterfly was restricted to vacant lots.
The last known specimens were taken:
23, 1941 by W. H. Lange at the "Presidio" (a few specimens
exist in museums).
The Xerces Blue flew generally
from mid-March to mid-April. Females laid their eggs on several
leguminous plants: Deerweed (Lotus
scoparius), Yellow-flowering Beach Lupine (Lupinus arboreus), and a blue-flowering lupine species (possibly Lupinus
micranthus). Apparently, Deerweed was the most commonly utilized and
preferred caterpillar food. All of the above foodplants are much more
widespread than was the Xerces Blue: Deerweed, for example, occurs
throughout the California coastal foothills. Close relatives of the
Xerces Blue utilize Deerweed and various lupine species at many
locations in the western United States. It appears that geographic
isolation and climate, rather than food-plant specialization, limited
Xerces to the San Francisco Peninsula.
the tiny wings of the last Xerces blue butterfly ceased to flutter.
our world grew quieter by a whisper and duller by a hue. "
Left: Glaucopsyche lygdamus xerces (upper-side) - Field Museum, Chicago
Right: (under-side variations) - California Academy of Science
What's in a Name? A
Xerxes (the 'c' is replaced by an
'x' and pronounced with a hard 'ks' sound in English) was king of Persia from
486 to 465 BC. A great deal of history revolves around the king and his reign
that ended in his murder and in-family fighting that killed several of his heirs.
The French entomologist Boisduval named the butterfly for King Xerxes, but
retained the French spelling, Xerces.
Extinction may not always
have to be forever:
Contrary to the popular
conservation aphorism, extinction may not always have to be forever.
Occasionally, the thoughtful reintroduction of an organism closely related to an
extinct type can result in the functional reconstruction of the animal or plant
thought to be lost in toto. The conditions permitting such a Lazarus
act are rare, and their employment raises all sorts of philosophical questions.
Still, reestablishment of species through their near relatives in restored
habitats may be an act worth considering in some cases. I
would like to nominate the Xerces Blue as a candidate for radical genetic
butterfly of the Presidio,
Vanished and mourned as extinct.
Wondrously, could it reappear,
Fluttering light in the grass.
Et resurrexit tertia die
Et ascendit in coelum
Iterum venturus est cum gloria
Glaucopsyche lydamus xerces.
"They . . . are simply the littlest of things that run the World. "
The United States is home to some 700 species of butterflies; 14 of them are listed as endangered or threatened by the U. S. Fish and Wildlife Service. Gone forever are the Xerces Blue, Sthenele Satyr, Pheres Blue, Strohbeen's Parnassius, and the Atossa Fritillary. Worldwide, the World Conservation Union cites 332 butterflies as being in trouble. But population data for most of the 20,000 known butterfly species is scant to nonexistent, and recent surveys in the Amazon River Basin suggest that another 2,000 species have yet to be discovered. We have no idea how many butterfly species are lost as we say goodbye to an acre of rain-forest with every heartbeat.
The Great Spirit surely
Psychologists have not begun to
ponder the emotional toll of the loss of fellow life. Nor have theologians
reckoned the spiritual impoverishment that extinction brings. To forget what we
had is to forget what we have lost. And to forget what we have lost means never
knowing what we had to begin with. That would be among the greatest tragedies of
Mark Jerome Walters, Program Director for Environment, Nathan Cummings
Foundation in New York City
to the Extinct (USA Butterflies)
Lone Mountain Cemetery was my last home. .
Glaucopsyche lygdamus xerces
I was drowned when army engineers built a dam.
Parnassius clodius strohbeeni
Air Force radar took my home in just a blip.
Speyeria nokomis coerulescens
Violet on Mt. Pinos was my sole food.
Speyeria adiaste atos
I took refuge on Twin Peaks, my cold oblivion.
Speyeria callippe extincta
San Francisco was my home.
I was highly prized by rich collectors.
Someone stole my shade and made me fly into the sun. . .
Butterflies of North America
Butterflies of California
(Public information from the U. S. G. S. website)
Silvery Blue (Glaucopsyche lygdamus [Doubleday])
- 1 1/4 inches (2.2 - 3.2 cm).
Upperside of male iridescent silvery blue with narrow dark borders; female darker blue with wide borders. Both sexes have white fringe. Underside gray-brown; both wings with row of white-ringed, round black spots. Subspecies xerces (Doubleday) and presudoxerces Emmel and Emmel have large white spots with or without black centers.
Males patrol near the host plants
for females. Eggs are laid singly on flower buds and young leaves of the host
plants. Caterpillars feed on flowers, seed-pods, and young leaves and are tended
by ants. Chrysalids hibernate.
One flight from March-June at low
elevations, June-August at high elevations.
Astragalus, Lotus, Lupinus,
Melilotus, Oxytropis, Lathyrus,
Vicia, and other species in the pea family.
Nectar from flowers including
A variety of locations including
open woods, coastal dunes, prairies, meadows, road edges, rocky moist woods, and
Central Alaska south to southern
California, Baja California, Arizona, New Mexico, and western Kansas. Along
northern United States east to Nova Scotia and south to Georgia.
is thought to be extinct. Its
historic range and its hostplant Astragalus
leucopsis in the Palos Verdes Hills in Los Angeles County, California is
largely extirpated, but an additional population was discovered in nearby San
Pedro. This subspecies has The Nature Conservancy rank of G1 - Critically
imperiled globally because of extreme rarity (5 or fewer occurrences, or very
few remaining individuals), or because of some factor of its biology making it
especially vulnerable to extinction. (Critically endangered throughout its
range). Subspecies xerces is GX - presumed extinct. Subspecies pseudoxerces
is rank T2.
Conserve all remaining habitat for
the Palos Verdes Blue. Investigate status and conservation needs of subspecies pseudoxerces.
T. C. and J. F. Emmel. 1973. The butterflies of southern California. Natural
History Museum of Los Angeles County, Los Angeles. 148 pages.
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California State and
J. W. , Real, H. G. , and D. K. Faulkner. 1992. Butterflies of Baja California.
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J. 1990. Bay Area Butterflies: The Distribution and Natural History of San
Hayward, Calif. : Hayward State University, Masters Thesis.
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Xerces Society and Its Pioneering Work on Conservation
Xerces Society is an international nonprofit organization dedicated to public
education concerning invertebrates and the carrying out of conservation projects
important to invertebrates' critical role in endangered ecosystems worldwide.
The Society was named for the Xerces Blue (Glaucopsyche xerces), the first
butterfly of North America documented to have been driven to extinction by the
activities of man. The Society aims not only at informing the public about the
importance of invertebrates (one of the largest and most significant segments of
the world's biota), but also at strengthening the basis of worldwide
conservation policy through scientific knowledge.
Society is presently headquartered at 4828 SE Hawthorne Blvd. , Portland, Oregon
97215-3252 (phone 505-232-6639, fax 503-233-6794).
and little-known organisms live within reach of where you sit.
Splendor awaits in minute proportions. . . "
E. O. Wilson
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