Palos verdes blue
The Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis) is a small endangered butterfly native to the Palos Verdes Peninsula in southwest Los Angeles County, California, United States. 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.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withThe Palos Verdes blue (G. l. palosverdesensis) is a localized subspecies of the silvery blue (G. lygdamus), which ranges over much of North America. 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 and an earlier flight period. The subspecies was described from 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, primarily by development of its habitat. The last three to six known individuals were seen and photographed in March, 1983, but the site they occupied was scraped shortly after for fire control. 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 food plant (common deerweed, Lotus scoparius) but shares physical and behavioral characteristics with the other now-extinct populations.
The Palos Verdes blue butterfly has a wingspan of only 25–30 mm (0.98–1.18 in). 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 colour. Both males and females have gray ventral wings with dark spots surrounded by white rings.
G. lygdamus palosverdesensis persists particularly on the Palos Verdes Peninsula, 15 miles south of Los Angeles, in a coastal sage scrub habitat. This subspecies is locally monophagous, or particular to one species of food plant. The entire subspecies was originally thought to be particular only to the locoweed or rattlepod (Astragalus trichopodus lonchus), but the population rediscovered in 1994 used common deerweed (Lotus scoparius) as its larval food plant. These two types of plants are fast becoming scarce on the Palos Verdes Peninsula because of housing development. Retention of these larval food plants is essential for conservation of the Palos Verdes blue.
Oviposition, laying of eggs on the larval food plant, occurs only once a breeding season for the Palos Verdes blue. There are at least four larval instars, or stages of development. After 7 to 10 days the larvae emerge and crawl to the base of the food plant where they pupate. Pupae remain in diapause until emerging as adults. The flight period and reproductive period occur together, beginning in late January and ending in early May. It is rare to see the Palos Verdes blue far from its home food patch, but research shows that males cover more distance and have longer periods of flight. Palos Verdes blues are a diurnal and panmictic subspecies. They are also non-migratory and very particular in their use of larval food plants. Their adult lifespan is only five days.
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 food plants. Recreational, commercial, or residential development of the Palos Verdes Peninsula is also a major concern in preservation of the food plants.
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 Palos Verdes blue include Defense Fuel Support Point in San Pedro and the Linden H. Chandler Preserve.In conjunction with other organizations, the Palos Verdes Peninsula Land 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", 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 Defense Logistics Agency 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."
