Rare
Guides
Corticaria varicolor
Corticaria varicolor is a minute beetle species in the family Latridiidae (plaster beetles), described by Fall in 1899. The species is known from a single observation in British Columbia, Canada, and is characterized by its small size and variable coloration as suggested by its specific epithet. Like other members of the genus, it likely inhabits moist, decaying organic matter. Very little is known about its biology due to its rarity and cryptic habits.
Cotinis aliena
Keys green June beetle
Cotinis aliena, commonly known as the Keys green June beetle, is a critically imperiled scarab beetle endemic to extreme southern Florida. The species has not been observed since 1998 and is known from only four localities: three in the Florida Keys and one in southern peninsular Florida. Its extreme rarity and apparent extirpation risk make it one of North America's most endangered beetle species.
Cradytes serricollis
Cradytes serricollis is a species of soft-bodied plant beetle in the family Melyridae. It belongs to a small genus of beetles distributed in western North America. The species is characterized by its distinctive serrated pronotum, as indicated by its specific epithet. It is rarely encountered, with limited observational records available.
Cratypedes lateritius
Nevada Red-winged Grasshopper
Cratypedes lateritius, the Nevada red-winged grasshopper, is a band-winged grasshopper in the family Acrididae. It is native to the Great Basin region of western North America and is rarely encountered in Wyoming. The species appears to have a two-year life cycle. Due to its scarcity, it has no documented economic importance.
Cratypedes lateritius lateritius
Cratypedes lateritius lateritius is a rarely collected grasshopper subspecies native to the Great Basin region of western North America. In Wyoming, it has been recorded only infrequently from sagebrush habitats. The subspecies appears to have a two-year life cycle, with adults present from May through August. Due to its scarcity, it has no documented economic importance.
Crinodessus
Crinodessus is a monotypic genus of predaceous diving beetles in the family Dytiscidae. The genus contains a single species, Crinodessus amyae, described by K.B. Miller in 1997. This genus belongs to the tribe Bidessini within the subfamily Hydroporinae.
Curalium
Curalium is a genus of true bugs (Hemiptera: Heteroptera) established in 2008 as the sole member of the family Curaliidae. The genus contains a single described species, Curalium cronini, known only from male specimens collected in the southeastern United States. Its distinctive physical and genetic characteristics warranted placement in a new family, representing a rare example of a higher-level taxonomic discovery in the 21st century.
Cuterebra mirabilis
Cuterebra mirabilis is a rare species of New World skin bot fly and the largest member of the rabbit-infesting group within the genus Cuterebra. As of 2009, the species was known from only three specimens, all collected in New Mexico. Like other Cuterebra species, it is an obligate parasite of lagomorphs, with larvae developing subcutaneously in host tissue. The specific epithet "mirabilis" (Latin for "extraordinary") reflects the species' remarkable size and striking appearance among bot flies.
Cyamops halteratus
Cyamops halteratus is a small fly species in the family Periscelididae, described by Sabrosky in 1958. The specific epithet 'halteratus' refers to the halteres, the modified hindwings characteristic of Diptera. Very few observations of this species exist in public databases.
Cymbopteryx fuscimarginalis
Cymbopteryx fuscimarginalis is a species of moth in the family Crambidae, described by Eugene G. Munroe in 1961. It belongs to the subfamily Odontiinae. The species is known from a single observation in Arizona, indicating it is likely rare or poorly collected.
Cynorhinella longinasus
Eastern Longnose Fly
Cynorhinella longinasus, the Eastern Longnose Fly, is a rare species of syrphid fly first described by Shannon in 1924. Adults are small, black flies with a distinctive elongated conical face. The species has been documented in a limited geographic range in the northeastern United States. Larval biology remains unknown.
Cyrtolobus acutus
Cyrtolobus acutus is a Nearctic treehopper species in the tribe Smiliini, first described from the southwestern United States in 1908. The genus Cyrtolobus comprises approximately 15 species distributed primarily in eastern and southwestern North America, characterized by their distinctive pronotal morphology. This species represents one of the less commonly encountered members of the genus, with specimen records indicating sporadic occurrence across arid and semi-arid regions.
Cyrtophyllicus chlorum
Chaparral Shieldback
Cyrtophyllicus chlorum is a rare species of shield-backed katydid in the family Tettigoniidae. It is the sole described species in the genus Cyrtophyllicus. The species has been documented in limited localities in California, with observations concentrated in the Winters area. Its rarity and restricted distribution make it of particular interest to entomologists and naturalists.
Dasycerus angulicollis
Dasycerus angulicollis is a species of rove beetle in the family Staphylinidae, described by Horn in 1882. It belongs to the subfamily Dasycerinae, a small and morphologically distinctive group within the rove beetles. The species is known from California, USA, with limited published information available regarding its biology and ecology. Members of the genus Dasycerus are characterized by their unusual body form among staphylinids.
Dasylechia atrox
Dasylechia atrox is a species of robber fly (family Asilidae) in the subfamily Laphriinae. Once considered ultra-rare, its true geographic range is now being defined primarily through photographic observations on iNaturalist, which have substantially outnumbered collected specimens. The species belongs to a small genus of distinctive, large-bodied robber flies.
Dercylinus impressus
Dercylinus impressus is a rarely encountered ground beetle (family Carabidae) and the sole species in the genus Dercylinus. Described by LeConte in 1853, this species is endemic to the United States with records from North America. The genus belongs to the subfamily Licininae and tribe Oodini. Very little is known about its biology, ecology, or habitat preferences due to its apparent rarity and limited collection records.
Diacanthous triundulatus
Diacanthous triundulatus is a species of click beetle in the family Elateridae. The genus Diacanthous is a small group within the click beetles, characterized by distinctive morphological features. Very few observations of this species exist in public databases, indicating it is either rare, cryptic, or undercollected.
Dichomeris pelta
Dichomeris pelta is a small moth in the family Gelechiidae described by Ronald W. Hodges in 1986. It is known from a limited range in the southeastern United States, with confirmed records from South Carolina and Florida. Adults are active across multiple seasons, with flight records spanning January through June and again in October and December, suggesting either a multivoltine life cycle or extended emergence patterns. The species belongs to a large genus of gelechiid moths, many of which are poorly known biologically.
Dichomeris solatrix
A small moth in the family Gelechiidae, described from a single location in Arizona. Known from only two observations and limited published records.
Dictyssa maculosa
Dictyssa maculosa is a species of planthopper in the family Tropiduchidae, first described from California by Doering in 1938. The species is known from a small number of records and is characterized by spotted wing patterns, as indicated by its specific epithet. It belongs to a genus of small, relatively obscure planthoppers within the diverse Fulgoroidea superfamily.
Diphyllostoma
false stag beetles
Diphyllostoma is a genus of three rare beetle species endemic to California, commonly known as false stag beetles. Adults are diurnal and active during the day. Females are flightless, while males have functional wings. Larval stages have never been observed, and the life history remains largely unknown. The genus represents the sole member of the family Diphyllostomatidae.
Diphyllostoma nigricolle
A small scarab beetle in the family Diphyllostomatidae, a rare and poorly known group endemic to western North America. The species was described by Fall in 1912 and is distinguished by its dark (black) neck or collar region, as indicated by its specific epithet. Members of this family are among the most enigmatic beetles, with very few specimens collected and limited biological data available.
Dipropus yaqui
Dipropus yaqui is a species of click beetle in the family Elateridae, genus Dipropus. It belongs to a diverse family characterized by the ability to right themselves using a prosternal spine that fits into a mesosternal groove, producing the characteristic clicking sound. The species is known from a single observation record, indicating it is either extremely rare, poorly surveyed, or potentially misidentified.
Discodon flavomarginatum
Discodon flavomarginatum is a soldier beetle (family Cantharidae) native to southeastern Arizona. First described by Charles Schaeffer in 1908 from the Huachuca Mountains, this species is characterized by its distinctive color pattern and 14 mm body length. It belongs to a genus of soft-bodied beetles whose biology remains poorly documented.
Dissosteira longipennis
High Plains Locust, High Plains Grasshopper
Dissosteira longipennis is a large band-winged grasshopper native to the shortgrass prairie of western North America. During the 1930s, it formed massive swarms causing extensive crop and rangeland damage, but has not swarmed since and is now considered very rare. It is one of two North American locust species, the other being the extinct Rocky Mountain locust (Melanoplus spretus). The species persists in small, localized populations in favorable habitats.
Dystaxia
Dystaxia is a genus of small beetles in the family Schizopodidae, a family historically associated with Buprestidae (jewel beetles) but now recognized as distinct. The genus was established by LeConte in 1866 and contains at least one described species, D. elegans Fall, 1905, recorded from California. Schizopodidae are small, somewhat flattened beetles with reduced elytra that leave much of the abdomen exposed.
Dytoscotes pacificus
Dytoscotes pacificus is a species of rove beetle in the family Staphylinidae, subfamily Phloeocharinae. It was described by Smetana and Campbell in 1980. The species is known from Oregon in the western United States. Very little information is available about its biology, ecology, or specific habitat requirements.
Eanus hatchi
Hatch's click beetle
Eanus hatchi, known as Hatch's click beetle, is a species of click beetle in the family Elateridae. The species is named in honor of entomologist Melville H. Hatch. Very little published information exists regarding its biology, distribution, or ecology. It belongs to a genus of click beetles characterized by the family's namesake clicking mechanism, a prosternal process that fits into a mesosternal cavity to produce a sudden snap used for righting the body when overturned.
Elatotrypes hoferi
Elatotrypes hoferi is a species of longhorn beetle in the family Cerambycidae, described by Fisher in 1919. It belongs to the tribe Callidiini within the subfamily Cerambycinae. The species is known from western Canada, with records from Alberta and British Columbia. Very few observations exist in public databases, suggesting it is either rare, cryptic, or undercollected.
Embolemus nearcticus
Embolemus nearcticus is a small parasitoid wasp in the family Embolemidae, a group of rarely encountered insects with distinctive wing reduction in females. The species is known from very few observations in North America, reflecting both its cryptic habits and the general scarcity of its family. Embolemidae are understudied, and most species are known from scattered records. E. nearcticus contributes to the limited documented diversity of this family in the Nearctic region.
Emmesa blackmani
Blackman's False Darkling Beetle
Emmesa blackmani is a species of false darkling beetle in the family Melandryidae, described by Hatch in 1927. It is known from a small number of observations in eastern Canada, primarily Québec. The species belongs to a genus of beetles associated with decaying wood and fungal habitats in forest ecosystems.
Epeoloides pilosulus
Macropis Cuckoo Bee
Epeoloides pilosulus is one of the rarest bees in North America, an obligate kleptoparasite of oil-collecting Macropis bees (Melittidae). It belongs to the tribe Osirini, a group of parasitic bees entirely dependent on oil-collecting bees as hosts. The species was thought extinct from the 1950s until its rediscovery in Nova Scotia in 2004, with subsequent records from Alberta, Ontario, Connecticut, Maine, New Hampshire, and Michigan extending its known range. Its survival depends on a three-way ecological relationship: E. pilosulus requires Macropis host bees, which in turn require oil-producing Lysimachia flowers for larval provisioning.
Epeolus splendidus
Splendid Cellophane-cuckoo Bee
Epeolus splendidus is a cleptoparasitic (cuckoo) bee species described by Onuferko in 2018. As a member of the genus Epeolus, it invades the nests of polyester bees in the genus Colletes, where females lay eggs that hatch into larvae that kill the host egg or larva and consume the stored pollen. The species name 'splendidus' refers to its attractive appearance, characterized by short black, white, red, and yellow hairs forming distinctive patterns. Like other Epeolus species, it lacks the branched hairs typical of pollen-collecting bees due to its parasitic lifestyle.
Erimerus
Erimerus is a genus of chalcidoid wasps in the family Torymidae, established by Crawford in 1914. It is the type genus of the subfamily Erimerinae, a small and poorly known group within the Torymidae. The genus is characterized by distinctive morphological features that separate it from other torymids, though detailed biological information remains scarce. Erimerus species are believed to be parasitoids, consistent with the biology of related torymids, but specific host associations are largely undocumented.
Esthesopus atripennis
Esthesopus atripennis is a click beetle species in the family Elateridae. The genus Esthesopus is a small group within the click beetles, characterized by particular morphological features of the antennae and pronotum. This species is known from a limited number of observations and museum specimens.
Eulonchus marialiciae
Eulonchus marialiciae is a species of jewelled spider fly in the family Acroceridae, endemic to the Great Smoky Mountains of eastern North America. Unlike its congeners, which are locally abundant across western North America, this species is known from only a few specimens collected within a small contiguous area. Adults are brilliantly coloured pollinators, while larvae are parasitoids of tarantulas.
Eumorsea pinaleno
Pinaleno monkey grasshopper
Eumorsea pinaleno is a wingless grasshopper endemic to the Pinaleno Mountains of Arizona. It belongs to the family Eumastacidae, commonly known as monkey grasshoppers. The species is known from very few observations, and its biology remains poorly documented.
Eunota houstoniana
Houston Tiger Beetle
Eunota houstoniana is a rare tiger beetle endemic to Texas, known from only a handful of observations. The species is restricted to salt pan habitats, making it one of the most geographically limited tiger beetles in North America. Its narrow distribution and specialized habitat requirements contribute to its conservation concern.
Euparagia
Euparagia is the sole extant genus of the subfamily Euparagiinae within family Vespidae. The group represents a geographically relict taxon with a formerly cosmopolitan distribution in past geological times, now restricted to desert regions of the southwestern United States and northwestern Mexico. The genus contains ten described species, most named by Bohart between 1938 and 1988. Biological knowledge is extremely limited; only Euparagia scutellaris has been studied, with females known to provision soil nests with weevil larvae.
Euphilotes pallescens calneva
Honey Lake Blue
Euphilotes pallescens calneva is a subspecies of butterfly in the family Lycaenidae, commonly known as the Honey Lake Blue. It was described by John and Thomas Emmel in 1998. As a member of the genus Euphilotes, it belongs to a group of small butterflies commonly called 'blue' butterflies, though specific details about this particular subspecies remain limited in available sources.
Euphoria casselberryi
Euphoria casselberryi is a species of flower scarab beetle in the subfamily Cetoniinae. It belongs to a genus known for colorful, bee-mimicking adults that are fast, erratic fliers with a distinctive flight mechanism where the elytra remain closed while the membranous hind wings deploy. The species was described by Robinson in 1937 and is known from limited records in the southwestern United States and northern Mexico.
Euphydryas anicia magdalena
Magdalena alpine butterfly
Euphydryas anicia magdalena is a subspecies of checkerspot butterfly endemic to the Magdalena Mountains of west-central New Mexico. It was originally described by W. Barnes and J.H. McDunnough in 1918. The subspecies is considered rare and elusive, inhabiting alpine environments at high elevations. It has been featured in conservation literature, most notably in Robert Michael Pyle's novel "Magdalena Mountain," which helped raise awareness of this distinctive black alpine butterfly. The subspecies is currently synonymized under Occidryas anicia in some taxonomic databases, reflecting ongoing revisions in checkerspot butterfly systematics.
Euplastius mimicus
Euplastius mimicus is a species of click beetle in the family Elateridae. The specific epithet 'mimicus' suggests potential mimicry, though this has not been confirmed in available literature. The genus Euplastius is part of the diverse click beetle family, characterized by the ability to right themselves when flipped using a prosternal process that fits into a mesosternal groove. Available records for this species are extremely limited.
Eupristocerus
Eupristocerus is a monotypic genus of jewel beetles (family Buprestidae) containing the single species Eupristocerus cogitans. The genus is classified within the tribe Coraebini, a group of buprestids characterized by their association with woody host plants. Eupristocerus cogitans is notable as the only coraebine buprestid known from North America north of Mexico.
Eurema salome
Salome yellow
Eurema salome is a small yellow butterfly in the family Pieridae, commonly known as the Salome yellow. It ranges from Peru northward through tropical America and is an extremely rare migrant to the lower Rio Grande Valley in Texas. The species inhabits forest openings, edges, and roadcuts, with adults active year-round in the tropics and from August to September in southern Texas.
Exepacmus johnsoni
Exepacmus johnsoni is a species of bee fly (family Bombyliidae) described by Coquillett in 1894. It belongs to the tribe Aphoebantini within the subfamily Anthracinae. The genus Exepacmus is part of a diverse group of bombyliid flies characterized by their parasitoid life history, with larvae typically developing in the nests of solitary bees or wasps. Very few observations of this species have been recorded, with only 7 documented occurrences in iNaturalist as of the available data.
Fallapion ellipticum
Fallapion ellipticum is a species of straight-snouted weevil in the family Brentidae. Members of this genus are characterized by their elongated rostrum and association with woody plants. The specific epithet 'ellipticum' refers to the elliptical body shape. Information on this species remains limited due to its rarity in collections and observations.
Fitchiella
Fitchiella is a North American genus of planthoppers in the family Caliscelidae. The genus contains five described species, including the notably rare F. robertsonii, which has been the subject of recent intensive study. Most species remain poorly known biologically.
Fitchiella mediana
Fitchiella mediana is a small planthopper species in the family Caliscelidae, described by Lawson in 1933. It belongs to a genus containing other rare and poorly known planthoppers. The species has been recorded from Arizona and California. Little is known of its biology compared to its congener F. robertsonii, which has been intensively studied in Iowa prairies.
Fitchiella melichari
A small planthopper in the family Caliscelidae, described by Ball in 1910. Records indicate presence in Arizona. Very little biological information is documented for this species specifically.