By Bobbie Stephenson, CNPS-SD Newsletter Editor
In January 2020, the USFWS announced that it is proposing to list the Hermes Copper butterfly (Lycaena Hermes), endemic to San Diego County and northwestern Baja California, as a threatened species under the federal Endangered Species Act. Habitat loss and fragmentation, and the increased frequency and magnitude of wildfires, is contributing to the butterfly's decline. The USFWS is proposing to designate about 35,000 acres of critical habitat for the butterfly in San Diego County.
The adult Hermes Copper feed on the nectar of California Buckwheat (Eriogonum fasciculatum), and lay eggs exclusively on Spiny Redberry (Rhamnus crocea) bushes. The adult butterflies mature, fly, and lay eggs from May through July. Eggs are laid singly on twigs of the host plant and they hibernate until the following spring. The larvae (caterpillars) eat the young leaves of the spiny redberry host plant. Both the California Buckwheat and spiny redberry are found in coastal sage scrub and chaparral habitats.
Hermes Copper occurs only in populations of Spiny Redberry but does not inhabit all Spiny Redberry populations. In California, Spiny Redberry grows in the foothills of the Pacific Coast Ranges and the western foothills of the Sierra Nevadas, and so surrounds the whole San Joaquin Valley. In Southern California it occurs along the coast and into eastern San Diego County west of the desert. In the U.S., Hermes Copper occurs only in San Diego County. The evergreen Spiny Redberry is in the Buckthorn family (Rhamnaceae). Spiny redberry typically grows one to two meters high and blooms from January through April. The Rhamnaceae, with 55 genera and 950 species worldwide, also includes our wild lilac (Ceanothus) species.
To read our chapter’s Plant Profile for Spiny Redberry click here.