Palos Verdes Blue Butterfly

Glaucopsyche lygdamus palosverdesensis Perkins & Emmel, 1977
Date of listing: 1980
Federal Status: Endangered
State Status: None

In 1994, on a small batch of southern California locoweed (Astragalus trichopodes var. lonchus), a sighting of the Palos Verdes Blue Butterfly renewed hopes for the survival of this lycaenid. At the time of the discovery of this population, the Palos Verdes Blue had not been seen for nearly ten years and was feared extinct.

Like many lepidopterans (moths and butterflies), the Palos Verdes Blue is restricted to a single host plant. The larvae are adpated to the particular balance of nutritional components which this locoweed provides. This butterfly goes through one generation per year, the adults emerging in early to mid spring, synchronously with the locoweed flowers, to mate and lay eggs. The larvae feed upon the seeds and flowers of the host plant, molting several times, and soon drop to the ground or enter locoweed seedpods to become pupae. During the summer and fall the pupae undergo transformation into adult butterflies and then emerge early the following spring. The males and females of this species are distinguished by a color difference, the males’ upper wing surfaces being bluish, those of the female being a darker, almost gray color.

The Palos Verdes Peninsula, on the coast south of Los Angeles, is a shrinking patch of coastal scrub community that has been under increasing pressure of urban development. Other factors in the decline of this community, and the locoweed host plant in particular, include weed control, off-road vehicle use, non-native plant invaders, and fire suppression. Competition for host plant space by a related butterfly may also be a factor.

Current efforts at preservation are aimed at restricting irresponsible use of the scrub habitat, replanting the host plant and a captive breeding and reintroduction program. Successful reestablishment of the appropriate locoweed along with protection of the habitat from development are necessary to ensure this butterfly’s future.

For further reading:
Arnold, R. A., 1987. Decline of the endangered Palos Verdes Blue Butterfly in California. Biological Conservation 40 (3): 203-217.

US Fish & Wildlife Service – Environmental  Conservation Online

Xerces Society

Butterflies and Moths of North America


Back to California Threatened and Endangered Species List