This copper is found in San Diego County, California and Baja County, Mexico.
WSU Vancouver
Geography
Range Map
Hermes copper (Tharsalea hermes) has a restricted range in San Diego county and in some areas in Northwestern Baja County, Mexico.
Study area
The study area for this assessment was for the populations found in San Diego county.
Our data comes from the research of Dan Marschalek at San Diego State University and continued to present.
Natural History
Species interactions
Host Plant
Hermes copper caterpillars feed on spiny redberry (Rhamnus crocea).
Closeup of a pale yellow Rhomnus crocea flower and stem.
Nectar Plants
Adults feed on nectar from the flowers of California buckwheat (Eriogonum fasciculatum).
Closeup of a pink California buckwheat flower.
Habitat
Hermes copper habitat consists of mixed woodlands, chaparral, and coastal sage scrub. This butterfly is limited to the range of its host plant, spiny redberry, and it has not been observed north of the San Diego area.
The most significant threats to habitat are fire and human development, which have both resulted in the loss of many Hermes copper colonies. 33% of undeveloped Hermes copper habitat is privately owned, not protected from development, and has not been surveyed for data. However, much of this butterfly's habitat is currently preserved or protected.
Closeup of a pale yellow Rhamnus crocea flower and stem.
Closeup of a pale yellow Hermes copper butterfly perched on a green stem.
California buckwheat stems and pink flowers.
Large California buckwheat bush next to a trail against a clear blue sky.
Hermes copper and habitat
Population Dynamics
Hermes copper is a generally sedentary butterfly, but other members of its family Lycaenidae have been known to disperse long distances from high wind events.
Females are generally observed dispersing over larger distances than males. Males tend to stay in a localized area to perch and wait for females.
This butterfly is considered one of the rarest in California.
Life Cycle
Life Cycle
Hermes coppers produce a single brood per year (univoltine). Adults fly May through July.
Adult
Males perch near a hostplant patch and wait for females, while females tend to disperse between the patches.
A Hermes copper butterfly perches on a plant.
Eggs
Females generally lay one egg per plant, which does not hatch until the following spring.
Caterpillars
Caterpillars feed on freshly sprouted spring redberry, rapidly developing to form their chrysalis.
This map from the USFWS Species Status Assessment for Hermes copper shows that a significant portion of southwestern habitat is developed. Additionally, most sites list this species as extirpated, even on conserved land.
A map of southwestern California near San Diego, showing where Hermes copper habitat is developed, urban, conserved, or able to be developed.
Wildfire Management
There are currently no conservation efforts targeting the Hermes copper. However, local land management efforts focus on reducing the frequency and occurrence of wildfire.
Management involves clearing vegetation to reduce fuel loads, as well as implementing electricity brownouts when winds are high. Wildfires can ignite when high winds blow trees into active power lines.
Though these efforts aren't particular to the Hermes, its habitat stands to benefit from them.
Population Trends
We analyzed four sites with Hermes copper, and three of those sites had declines. There was no association between changes in abundance and phenology.
Example of activity trends declining with no phenological shift for Hermes copper.
Example of activity trends declining with no phenological shift for Hermes copper.
