Rare
Guides
Sphiximorpha loewii
Orange Wasp Fly
Sphiximorpha loewii is a rare North American hoverfly in the family Syrphidae, commonly called the Orange Wasp Fly. The species exhibits pronounced wasp mimicry, with an orange and black color pattern that resembles vespid wasps. It is one of the most poorly documented members of the genus Sphiximorpha, with only a handful of verified observations recorded. The genus Sphiximorpha is notable for its highly specialized larval biology, with most species developing as inquilines in the nests of social wasps.
Spilomyia citima
Western Hornet Fly
Spilomyia citima, commonly known as the Western Hornet Fly, is a rare species of syrphid hoverfly first described by Vockeroth in 1958. It belongs to a genus renowned for exceptional mimicry of yellowjacket wasps, employing visual, behavioral, and acoustic deception. The species has been documented in Canada and the United States, though records remain sparse.
Stegea mexicana
Stegea mexicana is a moth in the family Crambidae, described by Munroe in 1964. It is known from a single locality in Veracruz, Mexico. Very little is documented about this species beyond its original description and basic taxonomic placement.
Steingeliidae
Steingeliidae is a small family of scale insects within the order Hemiptera, containing approximately 5 genera and 10 described species. The family was established by Morrison in 1927 and is classified within the superfamily Coccidoidea. Members are placed in the infraorder Coccidomorpha alongside other scale insects and mealybugs. The genus *Steingelia* is the type genus, described by Nasonov in 1908.
Stenomorpha mckittricki
Stenomorpha mckittricki is a species of darkling beetle in the family Tenebrionidae, originally described by Pierce in 1954. The genus Stenomorpha comprises elongate, slender beetles primarily distributed in arid and semi-arid regions of western North America. This species appears to be rarely encountered, with limited documented observations. As with other tenebrionids, it is likely associated with dry habitats and nocturnal activity patterns.
Stenoptilia mengeli
Mengel's Plume Moth
Stenoptilia mengeli is a small plume moth (family Pterophoridae) described by Fernald in 1898. It is known from Arctic regions of Greenland and Nunavut, Canada. The species is characterized by its ashy grey coloration with distinctive dark markings on the wings. It is among the least genetically divergent Stenoptilia species, showing close relationship to Stenoptilia islandicus.
Stephanidae
Crown Wasps
Stephanidae, commonly called crown wasps, are a family of solitary idiobiont ectoparasitoid wasps and the sole living members of the superfamily Stephanoidea. The family comprises approximately 365 extant species in 13 genera, plus four extinct genera known from Cretaceous and Tertiary fossils. They are considered the most basal lineage of Apocrita and are rare in collections, with nearly 95% of species described from single specimens. Their distinctive morphology includes a semicircular ocellar corona on the head and highly modified hind legs adapted for host location in wood.
Stethusa
Stethusa is a genus of small rove beetles in the family Staphylinidae, subfamily Aleocharinae. The genus was established by Casey in 1910 and is currently classified within the tribe Athetini. Members of this genus are part of the diverse aleocharine fauna of North America. Very few observations of this genus exist in biodiversity databases, suggesting either genuine rarity or undercollection.
Stizocera floridana
Stizocera floridana is a small longhorn beetle (Cerambycidae) described by Linsley in 1949. It is known from a single specimen collected in Lee County, Florida, and reaches approximately 13 mm in length. The species belongs to the tribe Elaphidiini within the subfamily Cerambycinae. Very little is known about its biology or ecology due to its rarity and limited documentation.
Stonemyia velutina
velvety stonian horsefly, Volutine Stoneyian Tabanid Fly
Stonemyia velutina is a rare horsefly endemic to California, first described in 1892. The species was not observed between 1942 and 2023, leading to a premature declaration of extinction in 1996. Its 2023 rediscovery confirmed continued survival, though knowledge of its biology remains limited. The species belongs to the family Tabanidae, a group of biting flies whose females typically require blood meals for egg development.
Strongylophthalmyiidae
Hardwood Flies
Strongylophthalmyiidae is a small family of slender, long-legged flies containing approximately 80 species across two genera: the monotypic Southeast Asian genus Nartshukia and the cosmopolitan Strongylophthalmyia. The family's phylogenetic relationships remain unresolved, having been variously classified with Psilidae or Tanypezidae. The majority of species occur in the Oriental and Australasian regions, with limited representation in the Nearctic and Palearctic.
Stygoporus
Stygoporus is a monotypic genus of diving beetles (family Dytiscidae) containing the single species Stygoporus oregonensis. The genus was described in 1994 based on specimens collected from an Oregon bathroom in 1984. No additional specimens were reported until 2014–2016, making this one of the most poorly known beetle genera in North America.
Stylogaster biannulata
thick-headed fly
Stylogaster biannulata is a species of thick-headed fly in the family Conopidae, subfamily Stylogastrinae. It is one of only two Stylogaster species known from North America. The species is distinguished from its congener S. neglecta by antennal proportions: in S. biannulata, the second antennomere is almost as long as the third, whereas in S. neglecta the second antennomere is notably shorter. Adults possess an extremely elongated proboscis that exceeds body length when fully extended.
Sympistis baloghi
Sympistis baloghi is a noctuid moth described from a single female specimen collected in south central New Mexico. The species was formally named by James T. Troubridge in 2008. Its known wingspan measures approximately 34 mm. Adults have been documented only in June, suggesting a narrow seasonal activity window.
Synneuron
Synneuron is a rare genus of flies in the family Canthyloscelidae, with four extant species distributed across the Holarctic region. The genus has an exceptional fossil record extending back to the Lower Cretaceous (ca. 125 Ma), with specimens from Australia and the Eocene of North America, supporting its status as a true Pangean clade that survived major vegetation transitions from gymnosperm to angiosperm dominance. Its ancient origins and relictual modern distribution make it significant for understanding dipteran biogeography and the impact of Cretaceous floral turnover on insect lineages.
Syntexis libocedrii
incense-cedar wood wasp, cedar wood wasp
Syntexis libocedrii is the sole extant representative of the family Anaxyelidae, a lineage with an extensive Mesozoic fossil record that makes this species a 'living fossil.' It exhibits a highly specialized reproductive strategy, ovipositing exclusively in wood of recently burned conifers including incense-cedar (Calocedrus), red cedar (Thuja), and juniper (Juniperus). The species is rarely encountered due to its cryptic habits and dependence on post-fire environments.
Systasea zampa
Arizona Powdered-Skipper
Systasea zampa, known as the Arizona Powdered-Skipper, is a spread-wing skipper butterfly in the family Hesperiidae. It occurs in the southwestern United States and Mexico, with records from Arizona and adjacent regions. The species is considered uncommon to rare in many parts of its range, with adults active in early spring. It is one of three species in the genus Systasea, all characterized by distinctive wing morphology.
Talanus mecoscelis
Talanus mecoscelis is a species of darkling beetle described by Triplehorn in 1968. It belongs to the genus Talanus within the family Tenebrionidae. The species is known from very few observations, with only two records documented on iNaturalist. Its distribution and biology remain poorly documented.
Tanaops coelestinus
Tanaops coelestinus is a species of soft-bodied plant beetle in the family Melyridae. The genus Tanaops belongs to the subfamily Malachiinae, commonly known as malachiid beetles or soft-winged flower beetles. Very few observations of this species exist in public databases, indicating it is either rare, poorly surveyed, or restricted in distribution. Members of this genus are generally associated with flowers and vegetation where they prey on small arthropods.
Tanystoma cuyama
Tanystoma cuyama is a species of ground beetle in the family Carabidae, described by Liebherr in 1985. The species is endemic to a restricted range in California, USA, specifically associated with the Cuyama Valley region from which it takes its specific epithet. It belongs to the subfamily Platyninae, a group of carabid beetles often associated with riparian and moist habitats. The species is known from limited collection records and iNaturalist observations, indicating it is either genuinely rare or undercollected.
Tecnophilus
Tecnophilus is a genus of ground beetles in the family Carabidae, established by Chaudoir in 1877. The genus contains two described species: Tecnophilus croceicollis and Tecnophilus pilatei. It belongs to the subtribe Agrina within the tribe Lebiini, subfamily Lebiinae. The genus is rarely encountered in collections and field observations.
Tecnophilus pilatei
Tecnophilus pilatei is a ground beetle in the family Carabidae, first described by Chaudoir in 1877. It belongs to the subfamily Lebiinae and tribe Lebiini. The species is known from the southwestern United States. Like other members of its genus, it is likely a nocturnal predator adapted to arid or semi-arid environments, though specific ecological details remain poorly documented.
Teloleuca
Teloleuca is a genus of shore bugs in the family Saldidae, established by Reuter in 1912. The genus comprises approximately five described species. Members of this genus are true bugs (Hemiptera: Heteroptera) within the infraorder Leptopodomorpha. Shore bugs in this family are generally associated with moist habitats near water bodies.
Temnostoma trifasciatum
Three-lined Falsehorn
Temnostoma trifasciatum is a rare species of syrphid fly found in eastern and central North America. Adults are strong mimics of solitary mason wasps (Eumeninae), exhibiting sophisticated behavioral and morphological mimicry. The species is associated with woodland habitats where larvae develop in moist decayed wood. Adults visit flowers for nectar and pollen.
Tesolasomus lanei
Tesolasomus lanei is a species of click beetle in the family Elateridae. The genus Tesolasomus is a small group within the click beetles, characterized by specific morphological features that distinguish it from related genera. This species is known from extremely limited records, with only a single observation documented on iNaturalist. The scarcity of data reflects either genuine rarity, restricted distribution, or insufficient survey effort rather than absence from suitable habitats.
Teuchocnemis bacuntius
Orange Spur Fly
Teuchocnemis bacuntius is a rare species of syrphid fly in the family Syrphidae, commonly known as the Orange Spur Fly. Adults are medium-sized hoverflies distinguished by orange coloration and sexually dimorphic leg modifications. The species has been documented in the eastern United States with historical records from Georgia and Texas, though it remains poorly known with larvae undescribed.
Trichinorhipis knulli
Knull's Metallic Wood-boring Beetle
Trichinorhipis knulli is a minute jewel beetle (family Buprestidae) endemic to southern California, where it occurs in Riverside and Imperial Counties. It is the sole member of its monotypic genus, distinguished from related genera by its entire elytra covering the full abdomen and broadly rounded pronotum lacking lateral margins. Males exhibit highly modified flabellate antennae with expanded lamellae bearing numerous olfactory sensillae, an adaptation for detecting female sex pheromones. The species is rarely encountered in the field; most specimens have been reared from dead branches of jojoba (Simmondsia chinensis). At 3.6 mm, it is among the smallest buprestids.
Trigonalidae
Trigonalidae is a family of parasitic wasps constituting the sole living members of the superfamily Trigonaloidea. With over 90 described species in 16 genera, these wasps exhibit a remarkably complex life history involving hyperparasitism. Females deposit thousands of minute eggs on or within leaves, which must be consumed by a caterpillar to initiate development. The family is divided into two subfamilies: Orthogonalinae (containing only Orthogonalys) and Trigonalinae. Trigonalidae has been proposed as the sister group to all Aculeata.
Trigonaloidea
Trigonaloidea is a monotypic superfamily of Hymenoptera containing the single family Trigonalidae, comprising approximately 90-110 cosmopolitan species. The superfamily is of uncertain phylogenetic placement within Apocrita, sometimes associated with Evanioidea but currently treated as distinct. Trigonalids exhibit highly unusual biology: eggs are laid on foliage and hatch only upon ingestion by sawfly or lepidopteran larvae, subsequently developing as hyperparasitoids of primary parasitoids within those hosts. The sole European species, Pseudogonalos hahnii, is the only representative recorded from Britain and Ireland, where it is rarely encountered and possibly declining.
Trigonogya reticulaticollis
Trigonogya reticulaticollis is a species of metallic wood-boring beetle in the family Buprestidae. It was described by Schaeffer in 1904 and is known from the Nearctic region. The species belongs to a small genus of buprestid beetles characterized by triangular body shapes. Available records for this species are extremely limited, with only one documented observation in iNaturalist.
Trigonurinae
Trigonurinae is a monogeneric subfamily of rove beetles (Staphylinidae) containing only the genus Trigonurus. The group has a Holarctic distribution with approximately nine described species. Most species occur in North America (seven species), with two in the western Palaearctic and two in China. The subfamily was established by Reiche in 1866.
Trimerotropis infantilis
Zayante Band-winged Grasshopper
Trimerotropis infantilis is a rare, narrowly endemic grasshopper restricted to a small portion of the Santa Cruz Mountains in California. It was described by Rentz and Weissman in 1984. The species occupies specialized sandy habitats and is of conservation concern due to its extremely limited geographic range.
Triopasites
Triopasites is a genus of cuckoo bees in the family Apidae, subfamily Nomadinae, and tribe Brachynomadini. The genus was described by Linsley in 1939 and contains at least two described species: T. penniger (Cockerell, 1894) and T. spinifera (Rozen, 1997). As cleptoparasitic bees, species in this genus do not construct their own nests but instead lay eggs in the nests of host bees.
Triraphis harrisinae
Triraphis harrisinae is a species of parasitoid wasp in the family Braconidae, first described by Ashmead in 1889. The genus Triraphis belongs to the diverse ichneumonoid wasp superfamily, members of which are predominantly parasitoids of other insects. This species is rarely encountered in collections and field observations, with only 8 observations recorded on iNaturalist as of the data cutoff.
Typhoctes striolatus
Typhoctes striolatus is a species of wingless wasp in the family Chyphotidae, a small group of parasitoid wasps closely related to velvet ants (Mutillidae). Like other chyphotids, this species exhibits extreme sexual dimorphism: females are apterous and resemble ants, while males possess wings. The genus Typhoctes is one of two genera in Chyphotidae and is characterized by reduced wing venation in males and specific antennal structures. Very few observations of this species exist in scientific databases.
Typhoctes williamsi
Typhoctes williamsi is a species of parasitoid wasp in the family Chyphotidae, a small family of stinging wasps within the order Hymenoptera. The genus Typhoctes contains only two described species, with T. williamsi being one of them. Members of Chyphotidae are poorly studied and rarely encountered, with most information about the family coming from scattered collection records rather than systematic research. The species is known from extremely few observations.
Ulochaetes
Lion Beetle
Ulochaetes is a genus of longhorn beetles (Cerambycidae) in the subfamily Necydalinae. The genus contains at least two described species: Ulochaetes leoninus, distributed in North America, and Ulochaetes vacca, found in Bhutan and China. Ulochaetes leoninus is notable for its striking wasp-mimicry, featuring yellow and black coloration and a slender body form that causes it to be frequently mistaken for a wasp or hornet. The genus is relatively small and poorly studied, with most ecological information derived from observations of the North American species.
Undulambia rarissima
Gold-lined Undulambia Moth
Undulambia rarissima is a small crambid moth described by Eugene G. Munroe in 1972. It is known from limited records in Florida, with adults active during two distinct periods: January through May and again in September. The species is considered rare, as reflected in its specific epithet. Larval biology remains poorly documented, though there is tentative association with Polystichum ferns.
Vanhornia
Vanhornia is a genus of small parasitoid wasps comprising four described species. It is the sole genus in the family Vanhorniidae, a group formerly placed in Proctotrupoidea but now classified in Diaprioidea. Species are known from North America, the Palearctic, East Asia, and Southeast Asia. All members are parasitoids of beetle larvae in the family Eucnemidae.
Vanhornia eucnemidarum
Vanhornia eucnemidarum is a species of parasitic wasp in the family Vanhorniidae, first described by Crawford in 1909. It is one of the few known species in this small family of Hymenoptera. The species is associated with eucnemid beetles, as indicated by its specific epithet. Very few observations exist in public databases, reflecting its rarity or cryptic nature.
Vecturoides
Vecturoides is a genus of soft-winged flower beetles (family Melyridae) established by Fall in 1930. The genus is currently classified as doubtful in GBIF, indicating taxonomic uncertainty regarding its validity or circumscription. Very few observations exist, with only 10 records on iNaturalist. As a poorly documented genus, most aspects of its biology remain unknown.
Venezillo microphthalmus
Small-eyed Venezillo Pill Woodlouse
Venezillo microphthalmus is a small terrestrial isopod in the family Armadillidae, endemic to California. The species exhibits the characteristic conglobation (pill-forming) behavior typical of its family, rolling into a defensive ball when disturbed. It is considered rare on the mainland and has documented populations on the Channel Islands. The species is believed to be declining in the San Francisco Bay Area due to competition from introduced woodlouse species.
Vermileonidae
wormlions
Vermileonidae is a small family of Brachycera flies comprising fewer than 80 described species in 11 genera. The family is notable for its unusual biology: larvae construct conical pitfall traps in sand to capture prey, while adults are slender, long-legged flies that visit flowers for nectar. Historically classified within Rhagionidae, Vermileonidae is now recognized as a distinct family due to marked morphological and biological differences. The group has a relictual distribution concentrated in arid regions of Africa and the western Mediterranean, with additional species in Asia and the Nearctic.
Williamsonia fletcheri
Ebony Boghaunter
Williamsonia fletcheri, commonly known as the ebony boghaunter, is a small dragonfly in the emerald family Corduliidae. It is one of North America's earliest-flying dragonflies, active in May and June. The species is strongly associated with acidic bog habitats and has a restricted range in the northeastern United States and southeastern Canada. It is considered rare across most of its range and is classified as endangered in Massachusetts.
Williamsonia lintneri
Ringed Boghaunter
Williamsonia lintneri, commonly known as the ringed boghaunter, is a small dragonfly in the emerald family Corduliidae. It inhabits acid bogs in the northeastern United States and southeastern Canada, with a restricted range spanning Wisconsin, Michigan, New England, New York, New Jersey, and Ontario. Adults are active early in the season, primarily during May and June. The species is distinguished by distinctive yellow rings on the abdomen and gray-black coloration.
Xubida punctilineella
Xubida punctilineella is a crambid moth described by Barnes and McDunnough in 1913. The species is known from very few observations, with records limited to Florida in North America. Like other members of the genus Xubida, it is a small moth, but specific details about its biology remain poorly documented due to its rarity in collections and limited study.
Xylophagidae
awl-flies, stink flies
Xylophagidae is a small family of lower brachyceran flies comprising nine extant genera and approximately 135 species. Commonly known as awl-flies or stink flies, these insects are characterized by elongated bodies that resemble ichneumon wasps, with a constricted base of the abdomen and three-segmented antennae. The family occurs across all biogeographical regions except the Afrotropics. Larvae are primarily associated with rotting wood, where many species are predatory on other insect larvae.
Xylophilus cylindriformis
Xylophilus cylindriformis is a species of false click beetle (family Eucnemidae) in the order Coleoptera. The species is known from a single observation record, indicating extreme rarity or limited detection in the field. Members of the genus Xylophilus are typically associated with dead or decaying wood, where larvae develop as saproxylic feeders. Adults are generally small to medium-sized beetles with elongated, cylindrical body forms.
Xylota bicolor
Eastern Orange-tailed Leafwalker
Xylota bicolor is a rare species of syrphid fly found across the eastern half of North America. Adults are medium-sized hover flies with distinctive black bodies and orange abdomens. Unlike many flower flies, adults rarely visit flowers, instead feeding on pollen from leaf surfaces. The larvae develop under bark in sap runs of deciduous trees.
Zabrops flavipilis
Zabrops flavipilis is a species of robber fly in the family Asilidae, first described by Jones in 1907. The species is characterized by yellowish pile (setae), as indicated by its specific epithet "flavipilis" (Latin: flavus = yellow, pilus = hair). Very few observations exist—only 9 records on iNaturalist—suggesting it is either rare, locally distributed, or underreported. Like other Asilidae, it is presumed to be an aerial predator of other insects.