California-endemic
Guides
Ablautus californicus
Ablautus californicus is a species of robber fly (family Asilidae) described by Wilcox in 1935. The genus Ablautus is currently undergoing taxonomic revision, with this species among those being studied to clarify species boundaries and relationships. Like other Asilidae, it is presumed to be a predatory insect both in larval and adult stages. The specific epithet indicates a California distribution.
Acleris santacrucis
Acleris santacrucis is a small tortricid moth described by Obraztsov in 1963. It is known only from California in western North America. The species has a wingspan of approximately 14 mm. Adults are active from June through August and again in October.
Acmaeodera pubiventris panocheae
Acmaeodera pubiventris panocheae is a subspecies of jewel beetle in the family Buprestidae, described by Westcott in 2001. It belongs to the nominate species A. pubiventris, a member of the diverse genus Acmaeodera that is especially well-represented in North American desert regions. The subspecies epithet "panocheae" refers to the Panoche Hills area in California, indicating its restricted geographic range within the broader distribution of the species. Like other members of this genus, adults are likely associated with flowers and host plants in arid environments.
Acrobasis caliginella
Acrobasis caliginella is a snout moth (Pyralidae: Phycitinae) described by George Duryea Hulst in 1878. The species is restricted to the southwestern United States, with confirmed records from California and Arizona. Larvae feed on multiple oak species (Quercus spp.), including coast live oak and interior live oak. Like other Acrobasis species, it likely develops as a concealed feeder in host plant tissues.
Acrodectes
Acrodectes is a genus of shield-backed katydids in the family Tettigoniidae, containing a single described species, Acrodectes philopagus. The genus was established by Rehn and Hebard in 1920. These insects belong to the diverse katydid group within Orthoptera, characterized by their elongated antennae and stridulatory sound production.
Acusana fastigor
Acusana fastigor is a species of leafhopper in the family Cicadellidae, described by DeLong in 1942. It belongs to the tribe Gyponini within the subfamily Iassinae. The species is known from California. Like other members of its family, it is presumed to feed on plant sap using piercing-sucking mouthparts, though specific host associations remain undocumented.
Adela singulella
fairy longhorn moth
Adela singulella is a species of fairy longhorn moth (family Adelidae) endemic to California. Described by Walsingham in 1880, it is distinguished by the extreme sexual dimorphism in antennae length typical of the family—males possess antennae up to three times the length of their forewings. The species has a restricted but disjunct distribution across coastal and montane regions of California, with larval development tied specifically to two Gilia species (Polemoniaceae).
Adranes dietzii
Adranes dietzii is a minute rove beetle in the subfamily Pselaphinae, described by Schaeffer in 1906. The species belongs to the tribe Clavigerini, a group known for myrmecophilous (ant-associated) habits. It has been recorded from California, USA. Like other members of its tribe, it likely exhibits specialized morphological adaptations for life with ants.
Aglaothorax gurneyi
Gurney's shieldback
Aglaothorax gurneyi, known as Gurney's shieldback, is a species of shield-backed katydid described by Rentz and Birchim in 1968. The species was originally described as Neduba gurneyi before being transferred to the genus Aglaothorax. It belongs to the tribe Apteropedetini within the subfamily Tettigoniinae. The species has been documented in California.
Agnippe laudatella
Agnippe laudatella is a small gelechiid moth with a wingspan of approximately 10.5 mm, endemic to California. The species is characterized by distinctive white forewings with complex brownish fuscous patterning. Larvae feed on Quercus (oak) species.
Agonopterix cajonensis
Agonopterix cajonensis is a small moth in the family Depressariidae, described by John Frederick Gates Clarke in 1941. It is known only from California in western North America. Adults have distinctive forewing patterning with grayish fuscous ground color overlaid with ocherous-white markings.
Alaudes californicus
Alaudes californicus is a species of darkling beetle in the family Tenebrionidae, described by Aalbu, Caterino & Smith in 2018. The species is known from California and is one of few representatives of the genus Alaudes documented in the region. As a recently described species, detailed biological information remains limited.
Alconeura necopinata
Alconeura necopinata is a species of leafhopper in the family Cicadellidae, subfamily Typhlocybinae, described by Griffith in 1938. It belongs to the tribe Dikraneurini, a group of small, often colorful leafhoppers. Records indicate occurrence in California. Very little specific biological information has been published for this species.
Aliatypus californicus
California folding-door spider, California folding trapdoor spider
Aliatypus californicus is a species of folding-door spider in the family Antrodiaetidae. It is found in the United States, specifically in California. The species constructs burrows with a hinged, folding trapdoor made of silk and soil debris. It is one of several species in the genus Aliatypus studied for its burrow architecture and mygalomorph spider systematics.
Allygianus varius
Allygianus varius is a species of leafhopper in the family Cicadellidae, first described by Beamer in 1938. It belongs to the subfamily Deltocephalinae and tribe Athysanini. The species is known from California. As a member of the Auchenorrhyncha, it is a phloem-feeding insect.
Allygiella clathrata
Allygiella clathrata is a species of leafhopper in the family Cicadellidae, first described by Ball in 1936. It belongs to the subfamily Deltocephalinae, a large and diverse group of leafhoppers. The species is known from California, USA. Like other leafhoppers, it is a sap-feeding insect that uses piercing-sucking mouthparts to feed on plant vascular tissues.
Amblonoxia fieldi
Amblonoxia fieldi is a species of scarab beetle in the family Scarabaeidae. It was described by Fall in 1908. The species belongs to the subfamily Melolonthinae, commonly known as May beetles or June beetles. Very little specific information is available about this particular species in the published literature.
Amblonoxia harfordi
Amblonoxia harfordi is a scarab beetle in the family Scarabaeidae, subfamily Melolonthinae. It is endemic to California and belongs to a genus of flightless, soil-dwelling beetles. The species is poorly documented in scientific literature, with most records coming from citizen science observations. It is active during spring and early summer.
Ammopelmatus pictus
Pictured Jerusalem Cricket
Ammopelmatus pictus, commonly known as the Pictured Jerusalem Cricket, is a species of Jerusalem cricket in the family Stenopelmatidae. It was first described by Scudder in 1899. The species is endemic to California, with documented occurrences in the Central Valley, Diablo Range, and Silicon Valley regions. As a member of the Stenopelmatidae family, it belongs to a group of large, flightless orthopterans often referred to as Jerusalem crickets or potato bugs.
Amydria californica
Amydria californica is a species of clothes moth in the family Tineidae. The species is known from California and is documented by a single observation record on iNaturalist. As a member of the Tineidae, it belongs to a family whose larvae typically feed on keratinous materials including wool, fur, feathers, and other animal-derived substances, though specific biology for this species remains undocumented.
Andrena auricoma
Golden-haired Miner Bee
Andrena auricoma, the Golden-haired Miner Bee, is a small solitary mining bee in the family Andrenidae. Females measure 8–10 mm in length, while males are smaller at 6–9 mm. The species is native to the western United States, with its distribution centered in California and relative rarity outside this state. It is a ground-nesting bee that excavates tunnels in soil for reproduction.
Andricus confertus
Convoluted Gall Wasp
Andricus confertus is a cynipid gall wasp endemic to California that induces distinctive pink, brain-like clustered galls on the underside of valley oak (Quercus lobata) leaves along the midrib. The species reproduces parthenogenetically, with female larvae initiating gall formation in summer and adults emerging the following spring. The galls are composite structures formed by multiple individual galls growing in close proximity.
Andricus opertus
Fimbriate Gall Wasp
Andricus opertus is a cynipid gall wasp that induces distinctive galls on California oaks. The species exhibits alternation of generations, with bisexual and unisexual forms producing different gall types. The bisexual generation creates elongate, spiky leaf galls, while the unisexual generation forms aborted bud galls. This species is part of the highly diverse Andricus genus, which contains numerous oak-associated gall wasps.
Anelastes californicus
Anelastes californicus is a species of false click beetle in the family Eucnemidae. The species is known from California and is represented by very few observations in natural history collections. Eucnemidae are a family of elateroid beetles commonly known as false click beetles or eucnemid beetles, distinguished from true click beetles (Elateridae) by subtle morphological differences.
Ankothrips yuccae
Ankothrips yuccae is a species of thrips in the family Melanthripidae, first described by Moulton in 1926. It is associated with Yucca whipplei as its host plant, on which it breeds without causing major damage. The species is found in California and is one of relatively few documented species in the genus Ankothrips.
Antispila aurirubra
Antispila aurirubra is a small North American moth in the family Heliozelidae, described by Annette Frances Braun in 1915. It is endemic to California and is associated with Cornus (dogwood) species as larval hosts. The species exhibits distinctive metallic coloration on the thorax and forewings.
Antron quercusechinus
urchin gall wasp
Antron quercusechinus is a gall-inducing cynipid wasp that induces the distinctive 'urchin gall' on oak trees. The gall is spherical, approximately 1.5 cm in diameter, and covered with prominent spines that give it a sea urchin-like appearance. The species primarily targets blue oaks (Quercus douglasii) but has been observed on other white oaks. Heavy infestations can produce thousands of galls on individual trees.
Aphalaroida californica
Aphalaroida californica is a species of jumping plant louse (psyllid) in the family Psyllidae, described by Tuthill in 1939. The specific epithet "californica" indicates its association with California. As a member of Sternorrhyncha, it is a phloem-feeding insect. Very little published information exists on its biology, host associations, or ecology.
Aphelosternus interstitialis
Aphelosternus interstitialis is a species of clown beetle in the family Histeridae, first described by John L. LeConte in 1851. The species is native to western North America, with confirmed records from California. Like other members of the subfamily Saprininae, it is likely associated with decomposing organic matter and carrion, though specific ecological details remain poorly documented. The genus Aphelosternus is a small group within the diverse Histeridae, and species-level biology for most members is not well studied.
Aphonopelma icenoglei
Aphonopelma icenoglei is a species of tarantula in the family Theraphosidae, described in 2016 from California. It is one of 14 new Aphonopelma species identified during a comprehensive taxonomic revision that reduced the previously recognized 55 U.S. species to 29 well-defined species. The species is named in honor of William Icenogle, who contributed specimens and locality data to the study. Like other members of the genus, it is a ground-dwelling burrower native to the southwestern United States.
Aplanusiella californiensis
Aplanusiella californiensis is a leafhopper species in the family Cicadellidae, described by Nielson and Haws in 1992. It belongs to the tribe Platymetopiini within the subfamily Deltocephalinae. The species is endemic to California, as indicated by both its specific epithet and documented distribution records. It is one of few species in the genus Aplanusiella, a group of small cicadellid leafhoppers.
Aptostichus
Aptostichus is a genus of mygalomorph trapdoor spiders in the family Euctenizidae, described by Eugène Simon in 1891. The genus contains 41 described species distributed primarily in southern California, with some species extending into northern California, Mexico, and the Channel Islands. These spiders are notable for constructing silk-lined burrows with thin wafer-like trapdoors, though unlike some related genera, they do not seal side chambers with additional trapdoors. Several species have been named after prominent figures, reflecting both scientific interest and public engagement in arachnology.
Aptostichus atomarius
San Bernardino hills trapdoor spider
Aptostichus atomarius, the San Bernardino hills trapdoor spider, is a wafer-lid trapdoor spider in the family Euctenizidae. First described by Eugène Simon in 1891, this species is native to the United States. Like other members of its genus, it constructs silk-lined burrows with wafer-like trapdoor lids. The species is part of a diverse genus of trapdoor spiders found primarily in California and surrounding regions.
Aptostichus miwok
Miwok Trapdoor Spider
Aptostichus miwok is a trapdoor spider species in the family Euctenizidae, described by arachnologist Jason Bond in 2008. The species name honors the Coast Miwok people, Indigenous inhabitants of coastal California from the Golden Gate northward. Like other Aptostichus species, it constructs silk-lined burrows with wafer-like trapdoor lids. The species belongs to a genus that has received notable attention for species named after celebrities and public figures.
Aptostichus sarlacc
Sarlacc Trapdoor Spider
Aptostichus sarlacc is a trapdoor spider species described by Jason Bond in 2012 from the Mojave Desert. The species epithet references the Sarlacc creature from George Lucas' Star Wars, a fictional desert-dwelling organism. It belongs to a genus of trapdoor spiders known for constructing silk-lined burrows with camouflaged trapdoor lids made of soil, vegetation, and silk. The species was among 33 new Aptostichus species described from the American Southwest in a major taxonomic revision.
Areniscythris brachypteris
Oso Flaco Flightless Moth, sand-dune grasshopper moth
Areniscythris brachypteris is a flightless moth in the family Scythrididae, described by Jerry A. Powell in 1976. It is endemic to coastal sand dunes of California and is notable among Lepidoptera for its reduced wings and inability to fly. The species has been observed in 90 iNaturalist records, suggesting it is documented but not abundant.
Arenivaga investigata
desert cockroach
Arenivaga investigata, the desert cockroach, is a species in the family Corydiidae endemic to the Colorado Desert of California. It is notable for its ability to absorb water vapor from unsaturated air above 82.5% relative humidity, a physiological adaptation that allows survival in one of the most arid environments on Earth. The species exhibits extreme sexual dimorphism, with wingless females and fully winged males. It inhabits sand dunes and is primarily found in subsurface microhabitats where temperature and moisture conditions remain favorable.
Arenivaga sequoia
desert cockroach, sand cockroach
Arenivaga sequoia is a species of desert cockroach in the family Corydiidae, described by Heidi Hopkins in 2014 as part of a major revision of the genus Arenivaga. This species belongs to a group known for remarkable adaptations to harsh, arid environments. Like other Arenivaga species, it exhibits dramatic sexual dimorphism, with females appearing markedly different from males. The species was described based on male specimens, with species separation relying on complex genital characters. It is one of 39 new species discovered during Hopkins' four-year revision, which increased the genus from nine to 48 species.
Argyrolacia bifida
Argyrolacia bifida is a species of moth in the family Gelechiidae, and the sole member of its genus. It was described by Keifer in 1936 and is known from California, North America. As a gelechiid moth, it belongs to a large family of small moths commonly known as twirler moths. The genus name Argyrolacia derives from Greek roots suggesting silver (argyro-) and some form of covering or garment (lacia), though the specific meaning and relevance to the species' appearance is not documented in available sources.
Argyrotaenia cupressae
Argyrotaenia cupressae is a small tortricid moth endemic to California. Adults fly from May through September and have a wingspan of approximately 18–19 mm. The species is notable for its specialized larval diet on cypresses, junipers, and coast redwood.
Aristotelia adenostomae
Aristotelia adenostomae is a small moth in the family Gelechiidae, commonly known as twirler moths. It was described by Keifer in 1933 and is known only from California. The species has forewings measuring 4.3–6 mm. Its larvae feed specifically on Adenostoma fasciculatum, a shrub in the rose family commonly called chamise or greasewood.
Aristotelia calens
Aristotelia calens is a small gelechiid moth described by Edward Meyrick in 1923. It is known from California, with a wingspan of approximately 11 mm. The forewings display a distinctive pattern of brown ground color with multiple white fasciae that are irrorated (sprinkled) with grey, along with characteristic black markings including spots on the costa and fold, and a streak on the fold. The hindwings are grey. It belongs to a genus of "twirler moths" whose larvae are known to specialize on particular host plants.
Arphia ramona
California orange-winged grasshopper
Arphia ramona, the California orange-winged grasshopper, is a band-winged grasshopper species in the family Acrididae. It is characterized by orange hind wings that are concealed at rest but visible in flight. The species occurs in western North America, with a strong association with California habitats ranging from Coast Ranges to interior locations. Males produce a crackling sound during flight through wing crepitation, a trait associated with mating behavior.
Aseptis pseudolichena
Aseptis pseudolichena is a noctuid moth endemic to southern California, first described in 2000. It occupies open pine-oak forest, foothill chaparral, and grassy scrub habitats across six counties. Adults are active from June to August and have been documented in only two iNaturalist observations, suggesting limited survey effort or naturally restricted abundance.
Athysanella krameri
Athysanella krameri is a species of leafhopper in the family Cicadellidae, described by Blocker in 1988. The species is known from California. As a member of the genus Athysanella, it belongs to a group of small, plant-feeding insects commonly associated with herbaceous vegetation. Specific biological details remain poorly documented in published literature.
Athysanella vanesca
Athysanella vanesca is a leafhopper species in the family Cicadellidae, described by Blocker and Hicks in 1992. The species is known from California and belongs to a genus of small, slender leafhoppers. Like other members of Cicadellidae, it is presumed to feed on plant sap using piercing-sucking mouthparts. The species was established based on morphological distinctions from congeners.
Atopetholus
Atopetholus is a genus of millipedes in the family Atopetholidae, order Spirobolida. The genus was established by Chamberlin in 1918 and contains approximately eight described species, all distributed in western North America, particularly California. Species in this genus are cylindrical millipedes characteristic of the Atopetholidae family.
Attalus sp-one-calif
Attalus sp-one-calif is an undescribed or provisionally named species of soft-winged flower beetle in the family Melyridae, known from California. It belongs to the large genus Attalus, which comprises numerous small, often brightly colored beetles associated with flowers and vegetation. The 'sp-one-calif' designation indicates a morphospecies or working name used in collections or regional surveys pending formal description. Like other Attalus species, it is likely a pollen feeder as an adult.
Atypoides riversi
California Turret Spider, turret spider
Atypoides riversi, commonly known as the California turret spider, is a medium-sized mygalomorph spider endemic to northern and central California. It constructs distinctive burrows topped with a turret-like structure made of soil, vegetation, and silk. Females are larger than males, with body lengths ranging from 13 to 18 millimeters. Research indicates this species represents a species complex, with multiple genetically distinct populations separated by geographic barriers.
Batrisodes mendocino
Batrisodes mendocino is a small rove beetle in the family Staphylinidae, first described by Casey in 1886. It is an ant-loving beetle (myrmecophile) that has been documented in California, USA. The species epithet refers to Mendocino County or the broader Mendocino region of coastal northern California. Like other members of its genus, it is likely associated with ant colonies, though specific ecological details remain poorly documented.