Rare
Guides
Acanthopteroctetidae
archaic sun moths
Acanthopteroctetidae is a small family of primitive moths containing two genera and seven described species. Commonly known as archaic sun moths, they are diurnal and often exhibit iridescent coloration. The family has undergone significant taxonomic revision, with molecular evidence now placing it in the superfamily Neopseustoidea rather than as the sole family in Acanthopteroctetoidea. Biological data remain scarce, with larval stages documented for only one species.
Acmaeodera carlota
Acmaeodera carlota is a small metallic wood-boring beetle in the family Buprestidae, described by H.C. Fall in 1931 from specimens collected near Globe, Arizona. It belongs to the 'tubulus-species group' within the genus, characterized by small size (<8 mm), black coloration with confused yellow maculations on the elytra, and membership in the 'Truncatae' group (prosternal margin nearly straight). The species is poorly known due to limited collection records and inadequate original description, making identification difficult without comparison to determined specimens.
Acmaeodera comata
Acmaeodera comata is a species of jewel beetle (family Buprestidae) in the genus Acmaeodera, described by John Lawrence LeConte in 1858. It belongs to the Nearctic fauna and is one of approximately 790 species and subspecies of Buprestidae recognized in North America. The species is part of the Acmaeodera (s. str.) subgenus and is included in the 'Truncatae' group, characterized by a nearly straight prosternal margin that is not retracted from the sides. Like other members of this large and taxonomically challenging genus, A. comata is poorly known biologically and lacks modern taxonomic revision.
Acneus beeri
Beer's false water penny beetle
Acneus beeri is a species of aquatic beetle in the family Psephenidae, known from a single female specimen collected east of Cascadia, Oregon in July 1940. The species belongs to the false water penny beetles, a group characterized by their flattened, oval body form adapted for clinging to submerged surfaces in flowing water. No additional specimens have been reported in the more than 80 years since its original description, making it one of the most poorly known North American beetle species.
Acrocera
small-headed flies
Acrocera is a genus of small-headed flies in the family Acroceridae. These flies are endoparasitoids of spiders, with larvae developing internally within arachnid hosts. The genus is one of the most species-rich in North America and includes regionally rare species such as A. orbiculus. Adults are rarely encountered due to their brief lifespans and elusive behavior.
Acroceridae
small-headed flies, hunch-back flies, spider flies
Acroceridae are a small family of approximately 520 species in 50 genera, characterized by their distinctive hump-backed thorax and disproportionately small head. Adults are primarily nectar feeders with exceptionally long proboscises, while larvae are obligate endoparasitoids of spiders. Many species exhibit bee or wasp mimicry. The family is cosmopolitan but nowhere abundant, with most species known from fewer than 10 specimens.
Acrophotopsis
Acrophotopsis is a genus of velvet ants (family Mutillidae) established by Schuster in 1958. Velvet ants are solitary wasps characterized by dense, velvety hair and aposematic coloration. Females are wingless and often mistaken for ants, while males possess wings. The genus is poorly documented with minimal observational records.
Aenictopecheidae
Aenictopecheidae is a rare family of true bugs (Hemiptera) with a worldwide distribution but limited species diversity. The family contains approximately a dozen described genera, with most species found in tropical and subtropical regions. The only North American representative, Boreostolus americanus, has been documented from mountain stream habitats in the western United States.
Aenigmatias eurynotus
Aenigmatias eurynotus is a species of scuttle fly in the family Phoridae, subfamily Aenigmatiinae. The genus Aenigmatias comprises rarely encountered, poorly known flies associated with army ant colonies. Only two observations of this species have been recorded on iNaturalist, indicating extreme rarity or difficulty of detection in the field. The species was described by Brues in 1914.
Aeoloplides fratercula
Northern Coast Bush Grasshopper
Aeoloplides fratercula, known as the northern coast bush grasshopper, is a spur-throated grasshopper species in the family Acrididae. It belongs to a genus of grasshoppers associated with coastal and salt marsh habitats. The species has been documented in California and is considered part of the North American grasshopper fauna, though detailed biological information remains limited.
Aethecerinus hornii
Horn's Aethecerinus Long-Horned Beetle
Aethecerinus hornii is a rare longhorned beetle (family Cerambycidae) endemic to Florida scrub habitat in Highlands and Lee counties. Described by Lacordaire in 1869, this species belongs to the tribe Trachyderini, a group known for bright coloration, flower-feeding behavior, and diurnal activity. The species is extremely restricted in range and poorly represented in collections, with only five observations documented.
Agabus audeni
Agabus audeni is a predaceous diving beetle in the family Dytiscidae. It was described by Wallis in 1933 from a single type specimen collected in south-central British Columbia, and remained known only from that record until its rediscovery in the eastern foothills of the Rocky Mountains in southern Alberta. The species is morphologically similar to A. browni, with which it can be confused without careful examination.
Aglaothorax longipennis
Santa Monica shieldback katydid, Santa Monica Mountains Shieldback
Aglaothorax longipennis is a shieldback katydid endemic to the United States, specifically known from the Santa Monica Mountains region of California. It belongs to the family Tettigoniidae, which includes katydids, crickets, and bush-crickets. The species was originally described as Neduba longipennis before being transferred to the genus Aglaothorax. It has been studied at Topanga State Park, indicating a restricted range within coastal southern California.
Agrilaxia texana
Agrilaxia texana is a species of jewel beetle in the family Buprestidae. It is known from scattered records in the south-central United States, with documented collections from northeastern Texas and northwestern Oklahoma. The species appears to be associated with oak habitats, particularly Quercus havardii (shinnery oak). Like other members of the genus Agrilaxia, it is presumed to be a wood-boring beetle with larvae developing in dead or dying woody host material.
Agrilus audax
Audacious Elm Agrilus
Agrilus audax is a large, striking jewel beetle in the family Buprestidae, distinguished by its black elytra and red pronotum with a densely pubescent median channel. First described from Texas in 1891, it remained exceptionally rare for over a century, with confirmed records from only a handful of specimens across Texas, Arizona, Missouri, Oklahoma, and Ohio. The species is associated with hardwood trees, particularly bur oak (Quercus macrocarpa) and slippery elm (Ulmus rubra), and is considered one of the most elusive North American buprestids.
Agrilus frosti
Agrilus frosti is a metallic wood-boring beetle in the family Buprestidae, described by Knull in 1920. It is found in North America, with documented occurrences in Canada (Manitoba, Nova Scotia) and the United States. The species is poorly known and rarely collected; in Missouri, only two specimens have been documented—one beaten from post oak at Lichen Glade Natural Area and another captured in a malaise trap in central Missouri.
Agrilus gillespiensis
Enchanted Rock Agrilus
Agrilus gillespiensis is a species of metallic wood-boring beetle in the family Buprestidae, described by Knull in 1947. The species is a west Texas specialty, with records from the Big Bend region and adjacent areas of New Mexico. Adults have been collected from flowers of Echinocereus enneacanthus carnosus (strawberry cactus) and Opuntia camanchica (tulip pricklypear cactus), suggesting a floral association uncommon for the genus. The specific epithet refers to Gillespie County, Texas, though the species has a broader distribution in the region. Like other members of the enormous genus Agrilus, it presumably develops as a larva in dead woody branches, though no confirmed larval host records are documented.
Aleptina arenaria
Aleptina arenaria is a small noctuid moth described in 2011. The species is known exclusively from White Sands National Park in New Mexico, where it inhabits the gypsum sand dune field. Its specific epithet references this specialized sandy habitat. The species is known from only two observations, making it one of the most geographically restricted moths in North America.
Allaporus pulchellus
A spider wasp species in the family Pompilidae, originally described as Planiceps pulchella by Banks in 1910 and later transferred to the genus Allaporus. The genus Allaporus is a small group of pompilid wasps, and A. pulchellus appears to be a rarely encountered species with minimal documented observations.
Allaporus smithianus
Allaporus smithianus is a species of spider wasp in the family Pompilidae. It was described by Cameron in 1893. The genus Allaporus is a small, poorly documented group within the spider wasps, and A. smithianus remains extremely rare in collections and observations. No verified biological observations of this species have been published.
Allenius
Allenius is a genus of lady beetles (family Coccinellidae) containing a single described species, Allenius iviei. The genus was established in 2012 and is notable for its extreme rarity and distinctive morphology. The sole species is known from only a few specimens collected in the northwestern United States.
Ameletus velox
Ameletus velox is a North American mayfly species described by Dodds in 1923. It belongs to the family Ameletidae, a group of predatory mayflies known for their distinctive larval morphology and behavior. The species is part of the Nearctic fauna with documented presence in North America. As with other Ameletus species, it likely inhabits cool freshwater streams, though specific ecological details for this species remain limited in available literature.
Ametastegia articulata
Ametastegia articulata is a species of sawfly in the family Tenthredinidae, first described by Klug in 1818. It belongs to the subfamily Allantinae and is recorded from eastern Canada. Like other sawflies in this genus, it is likely associated with herbaceous vegetation, though specific host plant relationships remain poorly documented. The species is represented by very few observations, indicating either genuine rarity or undercollection.
Ammopelmatus kelsoensis
Kelso Dunes Jerusalem Cricket, Kelso Jerusalem cricket
Ammopelmatus kelsoensis is a large, flightless orthopteran insect endemic to the Kelso Dunes of California. It belongs to the family Stenopelmatidae, commonly known as Jerusalem crickets. The species is distinguished from congeners by specific leg spine and spur characteristics, including short, spatulate apical tibial spurs and reduced ventral spines on the fore and hind tibiae. Adults are active in midsummer. The species has been collected exclusively from burrows of Rhachocnemis colonies, where it has been observed preying on nymphs of that genus.
Ammosphex anomalus
Ammosphex anomalus is a species of spider wasp in the family Pompilidae, originally described by Dreisbach in 1950 as Pompilus anomalus anomalus. The species was later transferred to the genus Ammosphex. It is part of the aculeate wasp group within Hymenoptera. Very limited biological information is available for this species, with only a single observation recorded in iNaturalist and minimal published literature. The genus Ammosphex contains species that are generally associated with hunting spiders as prey for their larvae, consistent with the biology of Pompilidae.
Amorophaga cryptophori
Amorophaga cryptophori is a species of clothes moth in the family Tineidae, first described by Clarke in 1940. It belongs to a genus characterized by distinctive morphological features related to the phallus structure. The species has been recorded from Idaho, USA. Like other tineid moths, it likely has larvae that feed on keratinous materials, though specific life history details remain poorly documented.
Ampedus miniipennis
Small Click Beetle
Ampedus miniipennis is a small click beetle in the family Elateridae, first described by LeConte in 1853. It is found across northern and eastern Canada, from Alberta to Newfoundland and Labrador, extending into the Northwest Territories. The species is rarely encountered, with very few documented observations.
Anaplectoides brunneomedia
Brown-lined Dart
Anaplectoides brunneomedia, commonly known as the brown-lined dart, is a noctuid moth restricted to a few localities in the Appalachian Mountains. The species was described by McDunnough in 1946 and remains poorly known due to its limited distribution and rarity. Adults are active during summer months. The specific epithet 'brunneomedia' refers to the brown median line on the forewing.
Anarta oaklandiae
Oakland's Cutworm Moth, Oakland's Dart
Anarta oaklandiae is a noctuid moth species described by James Halliday McDunnough in 1937. Originally placed in the genus Scotogramma, it was later transferred to Anarta. The species is assigned Hodges number 10234 in the North American moth numbering system. Very few observations exist, with only one documented record on iNaturalist.
Anasimyia distincta
short-spurred swamp fly
Anasimyia distincta, known as the short-spurred swamp fly, is a rare syrphid fly species documented in the northeastern United States and adjacent Canada. Adults are commonly observed on flowers where they feed on nectar and pollen. The species belongs to a genus whose larvae are aquatic and possess the characteristic rat-tailed morphology of eristaline hoverflies.
Anepsius montanus
Mountain Darkling Beetle
Anepsius montanus is a darkling beetle (Tenebrionidae) described by Casey in 1891. The species is known from Alberta, Canada, with very few documented observations. As a member of the genus Anepsius, it belongs to a group of tenebrionid beetles typically associated with dry, often montane habitats. The common name "Mountain Darkling Beetle" reflects its alpine or subalpine distribution pattern.
Anergates
Anergates is a genus of myrmicine ants containing the single species Anergates atratulus, an extreme workerless social parasite. The species lacks a worker caste and depends entirely on host colonies of Tetramorium ants for survival and reproduction. It is listed on the IUCN Red List of threatened species.
Anergates atratulus
Anergates atratulus is an extreme workerless social parasite (inquiline) ant that lives exclusively within colonies of Tetramorium host species. It is one of the most specialized ant parasites known, lacking a worker caste entirely and producing only sexual forms (males and queens). The species is IUCN Red-Listed and considered rare across its European range.
Anillinus jancae
Anillinus jancae is a small, eyeless ground beetle in the tribe Bembidiini. It was described by Thomas C. Barr in 1995 based on specimens from Kentucky. The species belongs to a genus of minute carabids adapted to subterranean or deep soil habitats. Like other Anillinus species, it exhibits troglomorphic traits including reduced pigmentation and vestigial eyes.
Anomalacra
Anomalacra is a genus of shining leaf chafers (subfamily Rutelinae) in the scarab beetle family Scarabaeidae. It was described by Thomas L. Casey in 1915 and contains a single described species, Anomalacra clypealis. The genus belongs to the tribe Anomalini and is classified within the subtribe Anomalina. Its taxonomic status has been flagged as doubtful in some databases.
Anthracopteryx
Anthracopteryx is a monobasic genus of click beetles (family Elateridae) endemic to the Front Ranges of Colorado, USA. The genus contains a single species, A. hiemalis, which is notable for its winter activity period—unusual among click beetles. The genus was established by Horn in 1891 and remains poorly represented in collections and online databases.
Anthracopteryx hiemalis
Anthracopteryx hiemalis is a small click beetle (family Elateridae) and the sole species in its monotypic genus. It is notable for winter activity, a rare trait among click beetles. The species has an extremely restricted endemic range in the Front Range of Colorado, USA, spanning from Laramie south to Westcliffe. As of 2017, it was documented in only two observations on iNaturalist and had no prior photographic records on BugGuide.net, indicating it is among the most poorly documented North American elaterids.
Apiocera chrysolasia
Apiocera chrysolasia is a species of flower-loving fly described by Cazier in 1982. It belongs to the family Apioceridae, a small group of brachyceran flies commonly known as apiocerid flies or sometimes 'flower-loving flies' due to their association with floral resources. The species epithet 'chrysolasia' derives from Greek roots suggesting golden or woolly appearance. Like other members of its family, it is likely associated with arid or semi-arid environments in western North America, though specific details remain poorly documented.
Aporinellus yucatanensis
A species of spider wasp in the family Pompilidae, described from the Yucatán Peninsula of Mexico in 1893. As a member of Aporinellus, it is presumed to be a solitary wasp that hunts spiders as prey for its larvae, though specific biological details remain undocumented. The species is known from very few records, with minimal observational data available.
Apsaphida eremna
Apsaphida eremna is a rare noctuid moth and the sole species in its monotypic genus. It is known exclusively from Arizona, where it was first described by John G. Franclemont in 1973. The species remains poorly documented with few verified observations.
Apsilocephala
Apsilocephala is a genus of flies in the family Apsilocephalidae, established by Kröber in 1914. The genus contains one extant species, Apsilocephala longistyla, and two fossil species: Apsilocephala pusilla and Apsilocephala vagabunda. The family Apsilocephalidae is a small, poorly known group within the order Diptera.
Apterocyclus
Kauai flightless stag beetles
Apterocyclus is a genus of flightless stag beetles endemic to the Hawaiian island of Kauai. The genus comprises five described species, ranging from 14 to 23 mm in length. These beetles represent the only native scarabaeoid beetles in the Hawaiian Islands. Three species (A. honoluluensis, A. kawaii, and A. waterhousei) have been confirmed living since the late 1960s, while others may be extinct. Historical collection data shows a dramatic decline, with over 130 specimens documented between 1871 and 1922 but very few found in recent decades.
Apterocyclus munroi
Apterocyclus munroi is a species of stag beetle in the family Lucanidae. The species was described from four specimens collected on Kauai, Hawaii in 1897. No confirmed observations have been made since the original collection, and the species is considered possibly extinct. It belongs to a genus of flightless stag beetles endemic to the Hawaiian Islands.
Apterocyclus waterhousei
Apterocyclus waterhousei is a rare, flightless stag beetle endemic to the Hawaiian island of Kauai. It belongs to a genus of flightless beetles found only in the Hawaiian Islands. The species has been documented in several locations on Kauai in recent years.
Apteroloma caraboides
Apteroloma caraboides is a species of primitive carrion beetle in the family Agyrtidae, described by Fall in 1907. It belongs to a small group of beetles considered basal to the staphyliniform lineage. The species is restricted to western North America and is rarely encountered in field collections.
Araeolepia
Araeolepia is a genus of small moths in the family Glyphipterigidae, subfamily Acrolepiinae. The genus was established by Walsingham in 1881. It belongs to the superfamily Yponomeutoidea, a group of microlepidoptera. Very few observations of this genus exist in public databases, suggesting it is either rare, poorly sampled, or restricted to specific habitats.
Araeopidius monachus
Araeopidius monachus is the sole species in the subfamily Araeopidiinae within the beetle family Ptilodactylidae. It is endemic to western North America, where adults are rarely encountered. The species exhibits an unusual three-year life cycle among beetles, with larvae feeding on woody material while adults appear to be non-feeding. Its biology remains poorly understood due to the scarcity of specimens and limited field observations.
Archoleptoneta
Archoleptoneta is a genus of small spiders in the family Archoleptonetidae, containing only two known species restricted to the United States. The genus was established by Gertsch in 1974 and is characterized by reduced eyes and troglobitic adaptations. These spiders are among the least studied North American arachnids, with very few observations recorded.
Arthroceras fulvicorne
Arthroceras fulvicorne is a species of snipe fly described by Nagatomi in 1966. It belongs to the family Rhagionidae and is classified within the subfamily Arthrocerinae. Three subspecies have been recognized: A. f. fulvicorne, A. f. nigricapite, and A. f. subsolanum. The species is known from a small number of observations, indicating it is either rare or underrecorded.
Arthroceras pollinosum
Arthroceras pollinosum is a species of snipe fly in the family Rhagionidae, first described by Samuel Wendell Williston in 1886. It belongs to the subfamily Arthrocerinae, a group characterized by distinctive antennal modifications. The species is known from very few observations, with only five records documented on iNaturalist as of the available data. Its specific epithet 'pollinosum' likely refers to a pollinose (dusty or pollen-covered) appearance, a common trait in this genus.