California-endemic
Guides
Battaristis pasadenae
Battaristis pasadenae is a small moth in the family Gelechiidae, described by Keifer in 1935. It is known from California in western North America. The species has a wingspan of approximately 11–12 mm and exhibits distinctive wing patterning with white markings on a fuscous background. Very few observations of this species have been recorded.
Bembidion corgenoma
Bembidion corgenoma is a small ground beetle in the family Carabidae, described by David Maddison in 2020. The species was named in honor of former California Governor Jerry Brown and his wife Anne Brown, following its rediscovery on their Colusa County ranch after a 55-year absence from scientific observation. The beetle was previously known only from 21 historical specimens collected between the 1920s and 1966, suggesting a significant population decline likely driven by habitat loss from urbanization and agricultural development in California's Central Valley and Los Angeles Basin.
Bembidion palosverdes
Palos Verdes Minute Intertidal Beetle
Bembidion palosverdes is a species of ground beetle in the family Carabidae, described by Kavanaugh & Erwin in 1992. It is endemic to the Palos Verdes area of California, USA. The species is known as the Palos Verdes Minute Intertidal Beetle, reflecting its apparent association with intertidal or coastal habitats. Like other members of the genus Bembidion, it is presumed to be a small predatory beetle, though specific ecological details remain poorly documented.
Bombus crotchii
Crotch's bumble bee, Golden State bumble bee, Crotch's bumblebee
Bombus crotchii, commonly called Crotch's bumble bee or the Golden State bumble bee, is a short- to medium-tongue bumble bee endemic to California and adjacent regions. The species is classified as endangered under the California Endangered Species Act and listed as imperiled globally by the IUCN. It has experienced severe population declines attributed to habitat loss, pesticide exposure, climate change, and inbreeding depression. The species is a dietary generalist and important pollinator of native plants and agricultural crops.
Brachinus pallidus
Brachinus pallidus is a bombardier beetle in the family Carabidae, first described by Erwin in 1965. Like other members of the genus Brachinus, it possesses the remarkable chemical defense system for which bombardier beetles are famous: paired glands that combine hydroquinones and hydrogen peroxide to produce a hot, noxious spray of benzoquinones when threatened. The species is known from California and represents part of the diverse North American fauna of this chemically defended ground beetle genus.
Brachypalpus cyanella
Longnose Catkin, Longnose Catkin Fly
Brachypalpus cyanella is a rare Nearctic syrphid fly described by Osten Sacken in 1877. Adults are flower-associated, feeding on nectar and pollen. Larvae are of the rat-tailed type, developing under tree bark in decaying sap. The species has a restricted distribution in southern and central California.
Bucculatrix ceanothiella
Bucculatrix ceanothiella is a minute moth in the family Bucculatricidae, first described by Annette Frances Braun in 1918. The species is known only from California, with a wingspan of approximately 6.5 mm. Adults are active during multiple periods throughout the year, and larvae are specialized leaf miners on Ceanothus species.
Bucculatrix ericameriae
Bucculatrix ericameriae is a small moth in the family Bucculatricidae, described by Annette Frances Braun in 1963. It is known only from California, where adults fly in March. The larvae feed on Ericameria arborescens, a shrub in the aster family. Like other members of its genus, it is commonly called a 'ribbed cocoon-maker moth' due to the distinctive ribbed structure of its larval cocoon.
Bucculatrix ochristrigella
Bucculatrix ochristrigella is a small moth in the family Bucculatricidae, first described by Annette Frances Braun in 1910. It is known only from California in western North America. Adults are active in April and have a wingspan of 11–12 mm. The larvae are leaf miners that have been reared on Madia gracilis, a species of tarweed in the sunflower family.
Bucculatrix quadrigemina
A small moth in the family Bucculatricidae, described by Annette Frances Braun in 1918. Known from California, where larvae mine leaves of Althaea rosea (hollyhock). Adults fly from January through June and again in October. The species exhibits typical bucculatricid biology: early instars are leaf miners, later instars feed externally creating holes, and pupation occurs in a white cocoon.
Bucculatrix separabilis
Bucculatrix separabilis is a species of moth in the family Bucculatricidae, described by Annette Frances Braun in 1963. It is known only from California, where it has been recorded as a leaf miner on Baccharis pilularis. As a member of the genus Bucculatrix, it is part of a group commonly known as 'ribbed cocoon-maker moths' due to the distinctive ribbed structure of their larval cocoons. The species is poorly documented in scientific literature beyond its original description.
Bucculatrix taeniola
Bucculatrix taeniola is a small moth species in the family Bucculatricidae, described by Annette Frances Braun in 1963. It is known from California, North America. The larvae feed on white sage, which may refer to Salvia apiana or Eurotia lanata. As a member of the genus Bucculatrix, it is commonly referred to as a 'ribbed cocoon-maker moth' due to the distinctive ribbed cocoons constructed by larvae of this genus.
Bucculatrix transversata
Bucculatrix transversata is a minute moth in the family Bucculatricidae, first described by Annette Frances Braun in 1910. It is known only from California, with a wingspan of approximately 7 mm. The species is associated with Ambrosia psilostachya (western ragweed), on which its larvae feed. Adults are active in July, with larval development occurring in October.
Burnettweldia corallina
Coral Gall Wasp
Burnettweldia corallina is a cynipid gall wasp that induces distinctive detachable galls on blue oaks (Quercus douglasii) in California. The species was formerly classified under the genera Disholcaspis and Holcaspis before its current placement in Burnettweldia. The wasp oviposits at the base of leaf petioles, and the resulting galls change color dramatically as they mature.
Bycombia
Bycombia is a monotypic genus of moths in the family Drepanidae, subfamily Thyatirinae. It contains a single species, Bycombia verdugoensis, described from southern California in 1927. The genus was established by Benjamin in 1938. Adults are active during winter and early spring.
Bycombia verdugoensis
Bycombia verdugoensis is a moth in the family Drepanidae, and the sole member of its genus. It was described by Hill in 1927 based on specimens from California. The species is known from extremely few records, with only two observations documented on iNaturalist. Its biology and ecology remain largely unknown due to this scarcity of data.
Caecidotea tomalensis
Tomales Bay isopod
Caecidotea tomalensis is a freshwater isopod in the family Asellidae, commonly known as the Tomales Bay isopod. It is known from California, United States, and is one of relatively few described species in the genus Caecidotea. The species was described in 1877 by Harford. Like other asellid isopods, it is likely benthic and adapted to aquatic environments, though specific ecological details remain poorly documented.
Caligodorus vandykei
Caligodorus vandykei is a species of dung beetle in the family Scarabaeidae, subfamily Aphodiinae. The species was described by Barret in 1931 and is known from California, USA. It belongs to a genus of small to medium-sized aphodiine scarabs associated with dung and decomposing organic matter.
Calisoga
Calisoga is a genus of mygalomorph spiders in the family Nemesiidae, first described by Ralph Vary Chamberlin in 1937. The genus comprises five species, all endemic to the United States. Calisoga spiders are notable for their distribution pattern around the Central Valley of California, which has made them a significant study system for understanding ring speciation dynamics in mygalomorph spiders. Genetic studies indicate this is a lineage-rich complex with complex evolutionary history.
Calisoga longitarsis
False Tarantula
Calisoga longitarsis is a mygalomorph spider in the family Nemesiidae, commonly known as the False Tarantula. It is one of several species in the genus Calisoga distributed around the Central Valley of California. The species has been studied as part of research on ring speciation dynamics in California mygalomorph spiders. It is frequently observed and photographed, with over 2,300 records on iNaturalist.
Callirhytis carmelensis
Mottled Acorn Gall Wasp
A cynipid gall wasp endemic to California that induces distinctive galls on acorns of coast live oak (Quercus agrifolia) and interior live oak (Quercus wislizeni). The galls form at the acorn attachment point, often preventing normal nut development. The species produces a honeydew secretion that attracts other insects. Despite being described in 1922, it remains uncommon and poorly studied relative to other California oak gall wasps.
Callirhytis perdens
Ruptured Twig Gall Wasp
Callirhytis perdens is a gall wasp in the family Cynipidae that induces distinctive stem galls on several oak species in California. Unlike many gall wasps where larvae develop entirely within attached galls, this species exhibits a unique life history where mature larval capsules are expelled from fissures in the gall and complete development on the ground. The species was formerly classified under the genus Andricus. It is considered locally abundant within its restricted range.
Callirhytis perfoveata
leaf ball gall wasp
Callirhytis perfoveata is a cynipid gall wasp endemic to California that induces distinctive spherical leaf galls on oak trees. Formerly classified as Andricus perfoveata, this species specifically targets coast live oak (Quercus agrifolia), interior live oak (Q. wislizeni), and occasionally California black oak (Q. kelloggii). The galls form embedded within leaf tissue, appearing as roughly spherical structures that emerge bright green and mature to brown.
Callirhytis quercusagrifoliae
bud gall wasp
Callirhytis quercusagrifoliae, commonly known as the bud gall wasp, is a cynipid gall wasp that induces galls specifically on the flower buds of coast live oaks (Quercus agrifolia) and interior live oaks (Quercus wislizeni). The species has been documented in California, North America. Like other cynipids, it manipulates plant tissue development through chemical secretions to create protective structures for its larvae.
Callirhytis serricornis
kernel flower gall wasp
Callirhytis serricornis is a cynipid gall wasp endemic to California that induces distinct bottle- or vase-shaped galls on oak trees. The species exhibits alternating generations with different gall phenotypes: first-generation galls are brown, while second-generation galls are red and green. It is restricted to two host oak species in the western United States.
Callophrys dumetorum
Lotus Hairstreak, Bramble Hairstreak, Coastal Green Hairstreak, Bluish Green Hairstreak, Oregon Green Hairstreak (subspecies C. d. oregonensis)
Callophrys dumetorum is a small lycaenid butterfly found primarily in coastal California. The species exhibits striking sexual dimorphism in wing coloration, with vivid green ventral surfaces and subdued brown dorsal surfaces. Taxonomic history of this species has been complex, involving lectotype disputes and temporary replacement of the name C. dumetorum with C. perplexa before ICZN Opinion 2291 reverted the changes in 2012.
Callophrys sheridanii lemberti
Lembert's Hairstreak
Lembert's Hairstreak is a subspecies of the Sheridan's Hairstreak butterfly, first described by Tilden in 1963. It is classified within the family Lycaenidae, commonly known as gossamer-winged butterflies. The subspecies is endemic to California and is associated with specific host plant relationships typical of hairstreak butterflies.
Caloptilia palustriella
Caloptilia palustriella is a leaf-mining moth in the family Gracillariidae, known only from California. The species was described by Braun in 1910. Its larvae feed on willows (Salix species), creating mines within the leaves.
Caloptilia reticulata
Caloptilia reticulata is a small moth in the family Gracillariidae, known exclusively from California, United States. The larvae are leaf miners on oaks, specifically documented on Quercus agrifolia (coast live oak) and Quercus wislizeni (interior live oak). As with other Caloptilia species, the larvae likely create blotch mines within oak leaves and may fold or roll leaves in later instars.
Calosaturnia
Calosaturnia is a small genus of giant silk moths in the family Saturniidae, first described by John Bernhard Smith in 1886. The genus contains three recognized species, all endemic to western North America. Taxonomic placement has been unstable; the group is sometimes treated as a subgenus of Saturnia. The genus is notable for its restricted geographic range and distinctive wing patterns.
Calosaturnia mendocino
Mendocino Silk Moth, Mendocino Saturnia Moth
Calosaturnia mendocino is a silkmoth in the family Saturniidae, first described as Saturnia mendocino by Behrens in 1876. It is endemic to California, United States. The species belongs to a small genus of North American saturniid moths.
Cameraria diabloensis
Cameraria diabloensis is a minute leaf-mining moth in the family Gracillariidae, described by Opler & Davis in 1981. The species is endemic to California, United States, and is associated with a specific host plant, Quercus chrysolepis var. nana. Its larvae create characteristic mines in the leaves of this oak species. The species epithet refers to Mount Diablo in California.
Cameraria mediodorsella
Cameraria mediodorsella is a minute leaf-mining moth in the family Gracillariidae. It is endemic to California, where larvae feed on several oak (Quercus) species. The species was described by Braun in 1908.
Cameraria serpentinensis
Cameraria serpentinensis is a leaf-mining moth in the family Gracillariidae, endemic to California. Adults have forewings 3.2–4.2 mm in length. The species is named for its association with serpentine soils, where one of its oak hosts occurs. Larvae create distinctive ovoid mines on several Quercus species.
Capnobotes spatulatus
Spatulate Longwing
Capnobotes spatulatus, known as the spatulate longwing, is a shield-backed katydid described in 1968. It belongs to the family Tettigoniidae, a group characterized by elongated antennae and stridulatory sound production. The species is endemic to western North America, with records primarily from California.
Capnobotes unodontus
one-tooth longwing
Capnobotes unodontus, the one-tooth longwing, is a shield-backed katydid in the family Tettigoniidae. It was described by Rentz and Birchim in 1968. The species is known from California and has been documented in limited observations.
Catocala hermia francisca
Catocala hermia francisca is a subspecies of underwing moth in the family Erebidae, first described by Henry Edwards in 1880. As a member of the genus Catocala, it possesses the characteristic bold, colorful hindwings that are concealed at rest by cryptic forewings. The subspecific epithet "francisca" indicates an association with the San Francisco region of California. Like other underwing moths, it is nocturnal and belongs to a group commonly studied by lepidopterists for their distinctive wing patterns and habitat associations.
Catocala mcdunnoughi
McDunnough's underwing
Catocala mcdunnoughi, known as McDunnough's underwing, is a moth in the family Erebidae described by Auburn Edmund Brower in 1937. It is endemic to California, where adults are active from June to August with likely one generation per year. The larvae feed on Quercus chrysolepis (canyon live oak). Like other underwing moths, it exhibits the characteristic cryptic forewings and colorful hindwings typical of the genus.
Ceanothia bicolor
Ceanothia bicolor is a species of psyllid (jumping plant louse) in the family Psyllidae, described by Jensen in 1957. As a member of the Sternorrhyncha, it is a sap-feeding insect associated with host plants. The genus Ceanothia is named after its association with Ceanothus plants. This species is known from limited collection records in California.
Cephennium aridum
Cephennium aridum is a species of minute rove beetle in the family Staphylinidae, subfamily Scydmaeninae. It was described in 2009 from California and is distinguished by its association with arid habitats. The specific epithet "aridum" refers to the dry conditions of its type locality. Members of this genus are among the smallest beetles, often less than 2 mm in length.
Ceratagallia loma
Ceratagallia loma is a species of leafhopper in the family Cicadellidae, first described by Oman in 1939. It belongs to the tribe Agalliini within the subfamily Megophthalminae. Distribution records indicate occurrence in California. As with many leafhopper species, detailed biological information remains limited in available literature.
Ceraticelus artemisiae
A small dwarf spider (subfamily Erigoninae) described from southern California in 2009. Often found co-occurring with its probable sister species Ceraticelus phylax, with which it shares distinctive male palpal bulb morphology. The genus Ceraticelus is taxonomically problematic due to inadequate definition and superficial treatment of diagnostic characters.
Ceratopsallus croceus
Ceratopsallus croceus is a species of plant bug in the family Miridae, first described by Van Duzee in 1918. It belongs to the large and diverse family of true bugs known as plant bugs or mirid bugs. The genus Ceratopsallus is part of the suborder Heteroptera, which includes the 'true bugs' with their characteristic piercing-sucking mouthparts.
Cerotainiops kernae
Cerotainiops kernae is a species of robber fly (Asilidae) described by Martin in 1959. The genus Cerotainiops contains small, slender robber flies often associated with arid or semi-arid environments. As a member of the Asilidae family, it is presumed to be a predatory insect, though specific behavioral and ecological data for this species remain undocumented in published literature.
Ceuthophilus inyo
Ceuthophilus inyo is a species of camel cricket described by Hubbell in 1936. It belongs to the family Rhaphidophoridae, a group of wingless crickets commonly known as camel crickets or cave crickets due to their humpbacked appearance. The species is native to North America, with records from California. As with other members of its genus, it likely inhabits dark, damp environments, though specific ecological details for this species remain limited.
Chalcedectus maculipennis
Chalcedectus maculipennis is a species of chalcid wasp in the family Chalcedectidae, first described by Ashmead in 1896. The species name 'maculipennis' refers to spotted wings. It belongs to the superfamily Chalcidoidea, a large group of tiny parasitoid wasps. Very little specific biological information has been published for this species.
Cheirodes californicus
Cheirodes californicus is a species of darkling beetle in the family Tenebrionidae, first described by George Henry Horn in 1870. The species epithet indicates its association with California. Like other members of Tenebrionidae, it is a ground-dwelling beetle adapted to arid and semi-arid environments. The genus Cheirodes is part of the diverse darkling beetle fauna of western North America.
Chersodromia insignita
Chersodromia insignita is a species of hybotid dance fly described by Melander in 1945. It belongs to the family Hybotidae, a group of predatory flies commonly known as dance flies. The species is known only from California, with very few documented observations.
Chimarocephala californica
Chimarocephala californica is a species of grasshopper in the family Acrididae, subfamily Oedipodinae. It was described by Bruner in 1905 and is endemic to California. The species belongs to a genus characterized by distinctive head morphology. Available records indicate limited observational data, with most documentation coming from museum collections rather than extensive field studies.
Chionodes morus
Chionodes morus is a small moth in the family Gelechiidae, described by Hodges in 1999. It is known only from California, with four observations recorded to date. The specific epithet 'morus' suggests a possible association with mulberry (Morus), though this relationship has not been confirmed. As a member of Chionodes, it belongs to a large genus of gelechiid moths whose larvae typically feed on various plant materials.