A butterfly endemic to the Palos Verdes Peninsula in southwestern California.
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Geography
Range Map
Palos verdes blue (Glaucopsyche lygdamus paloverdesensis) is a butterfly endemic to the Palos Verdes Peninsula in Southwestern California.
Study Area
The study area includes several locations in the Palos Verdes Peninsula. The range of Palos Verdes blue is limited to a very small and fragmented region.
Natural History
Species interactions
Host & Nectar Plants
Palos Verdes blue caterpillars feed on milkvetch (Astragalus trichopodus) and common deerweed (Lotus scoparius).
Image of large coast locoweed (milkvetch) plant in the sun.
Nectar Plants
Palos Verdes blue is dependent on the host plants for nectar as well, but will use other species if they are available.
Ant tending
Caterpillars are tended by carpenter ants, who protect them and receive honeydew. Pictured here is a related species, silvery blue (Glaucopsyche lygdamus incognitus) in western Washington.
A silvery blue caterpillar is tended by an ant.
Predation
Adult butterflies have a variety of predators, including spiders such as this silvery blue caught in a spider web in Lane County, Oregon.
Habitat
Palos Verdes blue habitat is only on the Palos Verdes peninsula in scrublands and rocky hills along the coast. This butterfly's host plant, locoweed (Astragalus trichopodus), grows well in rocky slopes and in well-drained soil. Although the distribution of suitable habitat extends outside of the Palos Verdes peninsula, this butterfly has not been observed in some areas where its presence is expected.
Palos verdes blue butterfly on one of its host plants, deerweed.
Pacific Ocean view from Ranchos Palos Verdes.
Coast locoweed bush with pale yellow flowers.
Palos verdes blue butterfly perched on a leaf.
Palos verdes blue and habitat
Population Dynamics
The palos verdes blue butterfly is a subspecies of the silvery blue (Glaucopsyche lygdamus). It is a relatively sedentary species, observed to rarely leave suitable habitat.
This butterfly is extremely rare and its populations very small; in 2018, the estimated population was 3. A status report conducted in 2018 by the Urban Wildlands Group projected a 100% probability of extinction within the next eight years.
Life Cycle
Adults
The butterflies fly in March. They produce one brood a year (univoltine), but they may sometimes undergo a two-year lifecycle where they overwinter twice and emerge as adults two years after hatching.
A Palos Verdes blue butterfly perches on a stem.
Eggs
Females lay eggs a few at a time on flower heads of host plants. The eggs hatch quickly.
Closeup of a Palos Verdes blue egg on a leaf.
Caterpillars
Caterpillars eat both locoweed and deerweed throughout their development. To camouflage themselves, they change color to match whichever part of the plant they are eating.
Palos Verdes blue larvae on a leaf.
Chrysalis
Palos Verdes blue usually overwinters in its chrysalis. Some caterpillars may overwinter if they undergo a two year life cycle. Pictured here is a related species, silvery blue (Glaucopsyche lygdamus).
Captive rear-and-release efforts have been underway since soon after rediscovery of this species, blue, but they have yet to establish what is considered a stable population.
Recovery Efforts
USFWS Recovery Plan
The United States Fish & Wildlife Service has a recovery plan in place for this species.
This map shows all historical data and reintroduction sites. Approximately every 5 years, the status of the Palos Verdes blue is assessed and reviewed.
A map of historical data for the Palos Verdes blue butterfly
Captive Rearing
Dr. Rudi Mattoni established a captive rearing program for the Palos Verdes blue in 1994, which was first run by the UCLA Department of Geography. Presently, the project is headed by Dr. Jana Johnson, a professor at Moorpark College, and run by the Urban Wildlands Group.
Captive rear-and-release programs have yet to establish a stable wild population of this butterfly.
Population Trends
We did not detect any trends in phenology or abundance for our palos verdes blue site spanning from 1994-2013.
Example of activity trends through time each year for palos verdes blue.
Example of activity trends through time each year for palos verdes blue.
