Palos Verdes Blue
Encyclopedia
The Palos Verdes Blue is a small endangered butterfly
native to the Palos Verdes Peninsula
in southwest Los Angeles County, California
. As its distribution has been proven to be limited to one single site it has one of the best claims to being the world's rarest butterfly.
of the Silvery Blue (G. lygdamus). It was described in 1977, shortly before it became one of the second groups of butterflies to be listed under the US Endangered Species Act
in 1980. It is distinguished from other subspecies of G. lygdamus by its slightly different patterning on the underside of the wing, an earlier flight period, and use of a locoweed (Astragalus trichopodus
) as a larval food plant. The distribution of the subspecies as described was the southern slope of the Palos Verdes Peninsula in coastal Los Angeles County.
The Palos Verdes blue butterfly was thought to be driven to extinction in 1983 by development of its habitat. Then, in 1994, the butterfly was rediscovered by Rick Rogers, Rudi Mattoni, and Timothy Dahlum at the Defense Fuel Support Point in San Pedro, which is located on the northern (inland) side of the Palos Verdes Peninsula. This new population lays eggs on an additional foodplant (common deerweed, Lotus scoparius
) but shares physical and behavioral characteristics with the other now-extinct populations.
, but the population rediscovered in 1994 used Lotus scoparius
(common deerweed) as its larval foodplant. These two types of plants are fast becoming scarce on the Palos Verdes peninsula because of housing development. Retention of these larval foodplants is essential for conservation of the Palos Verdes blue.
may occur with other lycaenid butterflies for the larval foodplant. A mutualism between ants and larvae has been observed during the instars of butterfly development. G. l. palosverdesensis has a host-parasite relationship with its larval foodplants, Astragalus lonchus and Lotus scoparius. There has also been observed predation on Palos Verdes blue by Western yellowjackets (Vespula pensylvanica
) at the Defense Fuel Point location.
" by the Fish and Wildlife Service on July 2, 1980. This listing also included city-owned Critical Habitat, plus comments and recommendations for species conservation. Insects are not currently protected by California laws.
In conjunction with other organizations, the Conservancy is installing and maintaining coastal sage scrub habitat on the slopes around the fuel tanks to benefit the blue butterfly. The Urban Wildlands Group, a nonprofit organization "dedicated to the conservation of species, habitats, and ecological processes in urban and urbanizing areas" (www.urbanwildlands.org), conducts the captive breeding program. This program is a collaboration with Moorpark College and is directed by Moorpark College professor Dr. Jana Johnson.
Since that time, the Defense Logistics Agency, which operates the facility, has funded habitat restoration and a breeding program for the blue butterfly. Honey, produced on the premises, is provided to the captive rearing program so the butterflies are able to feed on the same food source as its wild companions. Major Jason Pike, an entomologist for the DLA who has been monitoring the project, commented, "The military takes its responsibilities for endangered species on its properties very seriously, and DLA is pleased to provide support for the blue butterfly project."
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
native to the Palos Verdes Peninsula
Palos Verdes
Palos Verdes is a name often used to refer to a group of coastal cities in the Palos Verdes Hills on the Palos Verdes Peninsula, within southwestern Los Angeles County in the U.S...
in southwest Los Angeles County, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. As its distribution has been proven to be limited to one single site it has one of the best claims to being the world's rarest butterfly.
Overview
Palos Verdes Blue (G. lygdamus palosverdesensis) is a localized subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of the Silvery Blue (G. lygdamus). It was described in 1977, shortly before it became one of the second groups of butterflies to be listed under the US Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
in 1980. It is distinguished from other subspecies of G. lygdamus by its slightly different patterning on the underside of the wing, an earlier flight period, and use of a locoweed (Astragalus trichopodus
Astragalus trichopodus
Astragalus trichopodus is a species of legume known by the common name Santa Barbara milk vetch. It is native to southern California and Baja California, where it grows in several types of open habitat, including in the Transverse Ranges and Mojave Desert.This is a robust perennial herb producing a...
) as a larval food plant. The distribution of the subspecies as described was the southern slope of the Palos Verdes Peninsula in coastal Los Angeles County.
The Palos Verdes blue butterfly was thought to be driven to extinction in 1983 by development of its habitat. Then, in 1994, the butterfly was rediscovered by Rick Rogers, Rudi Mattoni, and Timothy Dahlum at the Defense Fuel Support Point in San Pedro, which is located on the northern (inland) side of the Palos Verdes Peninsula. This new population lays eggs on an additional foodplant (common deerweed, Lotus scoparius
Lotus scoparius
Lotus scoparius is a perennial subshrub in the family Fabaceae . The plant is a pioneer species found in dry areas of California, Arizona, and Mexico...
) but shares physical and behavioral characteristics with the other now-extinct populations.
Taxonomy and systematics
Glaucopsyche lygdamus palosverdesensis, is a subspecies of the G. lygdamus (Silvery Blue) species of butterfly found throughout North America. There are currently 11 subspecies of silvery blue. G. lygdamus palosverdesensis was first described in the 1970s and was distinguished from other G. lygdamus by its faster and early flight, wing color and wing spot patterns.Morphology
This butterfly has a wingspan of only 25–30 mm. The male has a bright silvery-blue dorsal wing outlined in a narrow line of black, while the female’s dorsal wing is a more brownish-gray color. Both males and females have gray ventral wings with dark spots surrounded by white rings.Habitat
G. lygdamus palosverdesensis persists particularly on the Palos Verdes Peninsula, 15 miles south of Los Angeles, in a coastal sage scrub habitat. This species is locally monophagous, or particular to one species of foodplant. The entire species was originally thought to be particular only to the locoweed or rattlepod Astragalus trichopodus lonchusAstragalus trichopodus
Astragalus trichopodus is a species of legume known by the common name Santa Barbara milk vetch. It is native to southern California and Baja California, where it grows in several types of open habitat, including in the Transverse Ranges and Mojave Desert.This is a robust perennial herb producing a...
, but the population rediscovered in 1994 used Lotus scoparius
Lotus scoparius
Lotus scoparius is a perennial subshrub in the family Fabaceae . The plant is a pioneer species found in dry areas of California, Arizona, and Mexico...
(common deerweed) as its larval foodplant. These two types of plants are fast becoming scarce on the Palos Verdes peninsula because of housing development. Retention of these larval foodplants is essential for conservation of the Palos Verdes blue.
Life Stages
Oviposition, laying of eggs on the larval foodplant, occurs only once a breeding season for PVB. There are at least 4 larval instars, or stages of development. After 7 to 10 days the larvae emerge and crawl to the base of the foodplant where they pupate. Pupae remain in diapause until emerging as adults. The flight period and reproductive period occur together for PVB, beginning in late January and ending in early May. It is rare to see PVB far from its home food patch, but research shows that males cover more distance and have longer periods of flight. Palos Verdes blue are a diurnal and panmictic species. They are also non-migratory and very particular in their use of larval foodplants. The PVB adult lifespan is only five days.Relationships with other species
Interspecific competitionInterspecific competition
Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...
may occur with other lycaenid butterflies for the larval foodplant. A mutualism between ants and larvae has been observed during the instars of butterfly development. G. l. palosverdesensis has a host-parasite relationship with its larval foodplants, Astragalus lonchus and Lotus scoparius. There has also been observed predation on Palos Verdes blue by Western yellowjackets (Vespula pensylvanica
Vespula pensylvanica
Vespula pensylvanica is a species of wasp in the genus Vespula.-Description:V. pensylvanica is a predatory species that feeds on a wide range of invertebrate taxa and this has great potential for negative impact on the native fauna in insular habitats...
) at the Defense Fuel Point location.
Laws
G. lygdamus palosverdesensis was listed as an "endangered speciesEndangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
" by the Fish and Wildlife Service on July 2, 1980. This listing also included city-owned Critical Habitat, plus comments and recommendations for species conservation. Insects are not currently protected by California laws.
Threats
The main threat to the Palos Verdes blue has been habitat destruction due to weeds and rototilling, which has negative effects on the essential larval foodplants. Recreational, commercial, or residential development of the Palos Verdes peninsula is also a major concern in preservation of the foodplants.Reintroduction
The Palos Verdes peninsula is split into the north and south slopes. On the north slope, reintroduction is suggested based on presence of deerweed (Lotus scoparius) and a native plant index number. The only habitat known so far on the north slope is the Defense Fuel Support Point location. The south slope has many more historic sites of Palos Verdes blue, which are all suggested for reintroduction, including any more sites containing locoweed (Astragalus). Particular sites of reintroduction and rehabilitation of the PVB include Defense Fuel Support Point in San Pedro and the Linden H. Chandler Preserve.In conjunction with other organizations, the Conservancy is installing and maintaining coastal sage scrub habitat on the slopes around the fuel tanks to benefit the blue butterfly. The Urban Wildlands Group, a nonprofit organization "dedicated to the conservation of species, habitats, and ecological processes in urban and urbanizing areas" (www.urbanwildlands.org), conducts the captive breeding program. This program is a collaboration with Moorpark College and is directed by Moorpark College professor Dr. Jana Johnson.
Since that time, the Defense Logistics Agency, which operates the facility, has funded habitat restoration and a breeding program for the blue butterfly. Honey, produced on the premises, is provided to the captive rearing program so the butterflies are able to feed on the same food source as its wild companions. Major Jason Pike, an entomologist for the DLA who has been monitoring the project, commented, "The military takes its responsibilities for endangered species on its properties very seriously, and DLA is pleased to provide support for the blue butterfly project."