The San Bruno elfin (''Callophrys mossii bayensis'') is a U.S. federally listed

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

that inhabits rocky outcrops and cliffs in coastal scrub on the

San Francisco Peninsula The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is Mountain View, south of Palo A ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to this habitat in

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. Its patchy distribution reflects that of its host plant, broadleaf stonecrop (''Sedum spathulifolium'').

Life cycle

Adults of this

butterfly Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...

emerge in February and March, when

nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...

providing flowers open. After mating, the female locates host plants on which to deposit her eggs, which hatch within a week. The tiny

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e first feed on the plant's vegetative structures; however, when the

stonecrop ''Sedum'' is a large genus of flowering plants in the family Crassulaceae, members of which are commonly known as stonecrops. The genus has been described as containing up to 600 species, subsequently reduced to 400–500. They are leaf succulen ...

's flowers begin to open, the larvae migrate upward and feed on the flowers themselves. By June most have completed their larval development at which time they evacuate from the host plant to

pupate A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

in ground litter. They lie dormant as pupae until the following spring, when the

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...

begins anew. The San Bruno elfin's life cycle holds an interesting aspect, common to many other

lycaenid Lycaenidae is the second-largest family of butterflies (behind Nymphalidae, brush-footed butterflies), with over 6,000 species worldwide, whose members are also called gossamer-winged butterflies. They constitute about 30% of the known butterfl ...

s regarding a

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

interaction with

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...

s. Elfin larvae excrete a sweet liquid known as honeydew which attracts ants. In exchange for honeydew, the ants often provide protection from harm by

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s and

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s, which are principal killers of foliage feeding insects.

Range and habitat

The San Bruno elfin is restricted to a few small

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...

s, the largest of which occurs on

San Bruno Mountain San Bruno Mountain is horst fault block mountain located in northern San Mateo County, California; with some northern slopes crossing over into southern San Francisco, it is also surrounded by San Francisco Bay and the cities of Brisbane, Colma ...

. Most of these areas, akin to the distribution of the host plant, are scattered on rocky slopes and ledges, especially east facing (McClintock, 1968). One of these niches is in the vicinity of the old quarry. Its

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

has been diminished in the past by

quarry A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their envi ...

ing,

off-road Off-roading is the activity of driving or riding in a vehicle on unpaved surfaces such as sand, gravel, riverbeds, mud, snow, rocks, and other natural terrain. Types of off-roading range in intensity, from leisure drives with unmodified vehicl ...

recreational vehicles A recreational vehicle, often abbreviated as RV, is a motor vehicle or trailer that includes living quarters designed for accommodation. Types of RVs include motorhomes, campervans, coaches, caravans (also known as travel trailers and camper ...

, and urban development as land development pressure on the San Francisco Peninsula continues to fester. To protect the rare San Bruno elfin as well as the

Mission blue butterfly The Mission blue (''Icaricia icarioides missionensis'') is a blue or lycaenid butterfly subspecies native to the San Francisco Bay Area of the United States. The butterfly has been declared as endangered by the US federal government. It is a su ...

a unique habitat management plan has been implemented on

, in which the lower slopes were opened for development while the higher areas were converted to public ownership as critical habitat. This strategy arose as a compromise result of years of conflict between

land developer Land development is the alteration of landscape in any number of ways such as: * Changing landforms from a natural or semi-natural state for a purpose such as agriculture or housing * Subdividing real estate into lots, typically for the purpose ...

s and conservationists regarding this unique piece of real estate, jointly prized for its outstanding habitat features and its economically valuable location. Current management on San Bruno Mountain and in other areas focuses on reduced

pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...

use, careful recreation management, and vegetation management. Several areas from which populations had been previously

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

are also being targeted for

revegetation Revegetation is the process of replanting and rebuilding the soil of disturbed land. This may be a natural process produced by plant colonization and succession, manmade rewilding projects, accelerated process designed to repair damage to a land ...

and reintroduction of the butterfly. Another population of San Bruno elfin is known to be established in Montara, on coastal bluffs about 25 miles (40 kilometers) south of San Bruno Mountain (Alling, 1986). This colony is near the

Fitzgerald Marine Reserve Fitzgerald Marine Reserve is a marine reserve in California on the Pacific Ocean, located just north of Pillar Point Harbor and Mavericks in the San Mateo County community of Moss Beach. Moss Beach is located approximately south of San Francis ...

. A third colony is found near

Rockaway Beach, California Rockaway Beach is a shoreline area of the Pacific Ocean in the southern portion of Pacifica, California, United States, approximately south of the city of San Francisco. It is located within a gently curving embayment with direct access via Rock ...

in Pacifica.

References

* Brown, R.M., "Larva and habitat of ''Callophrys fotis bayensis''" ''Journal of Research on the Lepidoptera'' 8: 49-50 (1969) * Curtis E. Alling, Michael Hogan, Lynn Alexander, et al., "Environmental Impact Report for the West Rockaway Beach Redevelopment Plan prepared for the city of Pacifica", Earth Metrics Incorporated, SCH #85127017, March, 1986 *

Elizabeth McClintock Elizabeth May McClintock (7 July 1912 – 19 October 2004) was a botany, botanist who was born in San Jacinto, California, United States, and grew up near the San Jacinto Mountains. She earned a Bachelor's degree in 1937 and a Master's degree in 19 ...

and Walter Knight, ''A Flora of the San Bruno Mountains, San Mateo County, California'', Proceedings of the California Academy of Sciences, Fourth Series, Volume XXXII, no. 20, pp. 587–677, November 29, 1968 * Emmel, J.F. and C.D. Ferris, "The biology of ''Callophrys'' (''Incisalia'') ''fotis bayensis'' (Lycaenidae)" ''Journal of the Lepidopterists' Society'' 26 (4): 237-244 (1972) {{Taxonbar, from=Q7413488 Callophrys

San Bruno San Bruno (Spanish for " St. Bruno") is a city in San Mateo County, California, United States, incorporated in 1914. The population was 43,908 at the 2020 United States Census. The city is between South San Francisco and Millbrae, adjacent to Sa ...

Endemic fauna of California

Natural history of San Mateo County, California

Fauna of the San Francisco Bay Area Critically endangered insects ESA endangered species Butterfly subspecies