Holarctic
Guides
Ameletus
Upland Summer Mayfly (A. inopinatus)
Ameletus is a genus of mayflies (Ephemeroptera) and the type genus of the family Ameletidae, circumscribed by Rev. A. E. Eaton in 1885. The genus is speciose, with approximately 30 bisexual species recognized in North America and additional species in Europe and Asia. Ameletus species occur in cold-water streams from small headwater brooks to larger rivers, with greatest diversity in mountainous regions of western North America. The genus includes A. inopinatus, the only predominantly montane mayfly species in the UK and a noted climate change indicator species.
Ameronothridae
Ameronothridae is a family of oribatid mites comprising approximately 8 genera and at least 30 described species. The family is predominantly distributed in Holarctic cold-temperate and polar coastal regions, with some populations occurring far inland on anthropogenic structures. Members are primarily intertidal inhabitants of rocky shorelines, with documented lichenivorous feeding habits. The family includes notable genera such as Ameronothrus, Halozetes, Alaskozetes, and Podacarus.
Amoebaleria helvola
Amoebaleria helvola is a species of small fly in the family Heleomyzidae, first described by Hermann Loew in 1862. The species was originally placed in the genus Scoliocentra before being transferred to Amoebaleria. Heleomyzid flies are generally associated with decaying organic matter, though specific ecological details for this species remain poorly documented. It is one of several species in the genus Amoebaleria, which is distributed across the Holarctic region.
Ampedus
click beetles
Ampedus is a large genus of click beetles (Elateridae) comprising approximately 461 recognized species with a cosmopolitan distribution concentrated in the Holarctic region. Adults are characterized by their ability to spring into the air using a click mechanism for predator avoidance. The genus exhibits substantial size variation, with North American species ranging from 3–4 mm to 13–14 mm. Larvae are saproxylic, developing in decaying wood, while adults feed on pollen. Multiple European species are considered endangered due to logging pressures on their forest habitat.
Ampedus nigrinus
Black Click Beetle
Ampedus nigrinus is a click beetle species in the family Elateridae, commonly known as the Black Click Beetle. It has a Holarctic distribution with records from multiple Canadian provinces including Alberta, British Columbia, Labrador, and Manitoba. The species belongs to a family characterized by the distinctive clicking mechanism used for righting themselves when overturned.
Amphipyra tragopoginis
Mouse Moth
Amphipyra tragopoginis, the Mouse Moth, is a widespread noctuid moth with a Holarctic distribution. The species has undergone significant population decline in the UK, dropping over 80% between 1970 and 2016. Its genome has been sequenced, revealing an 806 Mb assembly with 13,359 protein-coding genes. The species is notable for its unusual flight behavior and attraction to sugary baits rather than light.
Anaplectoides
green arches (for A. prasina)
Anaplectoides is a genus of moths in the family Noctuidae, established by McDunnough in 1929. The genus comprises at least 13 described species distributed across the Holarctic and Oriental regions. The best-known species is Anaplectoides prasina (green arches), a widespread Palearctic moth. Some species, particularly A. virens, are recognized as agricultural pests due to their polyphagous herbivorous habits.
Anaplectoides prasina
Green Arches
A medium-sized noctuid moth with distinctive green forewings marked by dark green or blackish patterning. The species exhibits notable color polymorphism, with forms ranging from pale whitish-green to dark brownish-grey. Adults are active from May to August across a broad Holarctic distribution. Larvae are broad generalist feeders on both herbaceous plants and hardwood trees.
Anasimyia
swamp flies
Anasimyia is a genus of wetland hoverflies (Syrphidae) characterized by aquatic larval development. The genus was historically treated as a subgenus of Lejops but has been elevated to full generic status based on morphological and molecular evidence. Adults are associated with marshy and aquatic habitats. The genus includes approximately 20 described species distributed primarily across the Holarctic region.
Anastrangalia
Anastrangalia is a genus of longhorn beetles in the family Cerambycidae, subfamily Lepturinae. The genus was established by Casey in 1924 and contains approximately 12 recognized species distributed across the Holarctic region. Species in this genus are characterized by their elongated bodies and often exhibit reddish or orange coloration. The genus includes both Eurasian and North American species, with some taxa showing transcontinental distributions.
Ancylis
Ancylis is a genus of tortricid moths in the subfamily Olethreutinae, tribe Enarmoniini. Species are commonly known as leafrollers or leaf folders, with larvae that construct silk shelters by folding or rolling host plant leaves. The genus has a Holarctic distribution with some species also recorded from the Oriental region and South America. Several species are economically significant agricultural pests, including the strawberry leafroller (A. comptana) and the jujube leafroller (A. sativa). Taxonomic revision using DNA barcoding has clarified species boundaries, revealing that presumed Holarctic distributions were often due to misidentification.
Ancylis
Ancylis is a genus of tortricid moths (Lepidoptera: Tortricidae) commonly known as leafroller moths. Species in this genus are typically small moths with mottled or banded forewings. Many are univoltine and associated with specific host plants, with larvae that fold or roll leaves of trees and shrubs. The genus has a Holarctic distribution with some species also recorded from Asia. Several species are of economic importance as pests of fruit crops and forestry trees.
Ancylis uncella
Bridge Roller
Ancylis uncella is a small tortricid moth with a Holarctic distribution spanning the Palearctic region and North America. First described from the Vienna area in 1775, it has been recorded across Europe and was recently confirmed from China. The species is distinguished by reddish-brown forewings with grey dorsal spots and light costal lines. Larvae feed on birch and heather.
Andrena barbilabris
Bearded Miner Bee, Long-lipped Miner, Sandpit Mining Bee
A solitary mining bee with a Holarctic distribution, found across Europe, northern Asia, and North America. Females excavate nesting burrows in sandy soils, provisioning cells with pollen and nectar before laying single eggs. The species exhibits sexual dimorphism in coloration and is active from early spring through mid-summer.
Anisobas
Anisobas is a moderately diverse genus of parasitoid wasps in the family Ichneumonidae. The genus is distributed across the Holarctic and Indo-Malaysian regions, with seven species currently known from the Nearctic region. Members of this genus are parasitoids, with at least one species (Anisobas coloradensis) having documented host associations with Lycaenidae butterflies.
Anisotoma
slime mold beetles, round fungus beetles
Anisotoma is a genus of small beetles in the family Leiodidae, commonly known as slime mold beetles or round fungus beetles. The genus contains at least 20 described species, with six monophyletic species groups comprising 35 known species including 13 described in a 1979 revision. These beetles are specialized associates of slime molds (Myxomycetes). The genus originated in North America from a Holarctic common ancestor shared with the related genus Agathidium, subsequently dispersing to Palearctic and Central American regions.
Anthophora
Common Digger Bees, Digger Bees
Anthophora is a large genus of solitary bees in the family Apidae, comprising over 450 species across 14 subgenera. These bees are most diverse in the Holarctic and African biogeographic regions. All species are solitary, though many nest in large aggregations. Nearly all species excavate nests in soil, either in banks or flat ground, with larvae developing in waterproof-lined cells without cocoons. Some species, notably Anthophora bomboides, are bumble bee mimics and construct distinctive turret-like nest entrances.
Anticheta
Anticheta is a genus of marsh flies in the family Sciomyzidae, commonly known as snail-killing flies. The genus comprises 15 described species divided into two subgenera: Anticheta (14 species) and Paranticheta (1 species). Species within this genus are associated with moist habitats and share the family-wide trait of predation on gastropods. The genus was established by Haliday in 1839 and has a primarily Holarctic distribution.
Antistea
dwarf sheet spiders
Antistea is a genus of dwarf sheet spiders in the family Hahniidae, established by Eugène Simon in 1898. The genus contains only two species: A. brunnea (Palearctic) and A. elegans (Nearctic), together forming a Holarctic distribution pattern. These spiders are among the least commonly encountered hahniids due to their small size and cryptic habits.
Apamea
Cutworm moths, Rustic shoulder-knot moths
Apamea is a genus of moths in the family Noctuidae, commonly known as cutworm moths or rustic shoulder-knot moths. The genus contains numerous species that are typically medium-sized with cryptic, mottled forewings in shades of brown, gray, and ochre. Several species are significant agricultural pests, with larvae feeding on cereal crops and grasses. Species-level identification is notoriously difficult due to extensive individual variation and overlapping morphological features.
Apamea zeta
Northern Arches, Zeta Moth
Apamea zeta is a medium-sized noctuid moth with a Holarctic distribution spanning Europe and northern North America. Adults are active from July to August in Britain and display variable gray-green forewings with distinctive black markings. The species exhibits notable morphological variation across its range, with several described forms and subspecies. Larvae are cutworms that feed on grasses, including fescues in alpine tundra habitats.
Apatania
Apatania is a genus of caddisflies in the family Apataniidae comprising at least 90 described species. The genus has a Holarctic distribution, with species recorded across Europe, Asia, and North America. Several species have been studied in detail for their larval morphology, life cycles, and behavior. Some species, including A. muliebris, are known to reproduce parthenogenetically.
Apataniidae
Early Smoky Wing Sedges
Apataniidae is a family of caddisflies (Trichoptera) commonly known as early smoky wing sedges. The family contains approximately 18 genera and at least 180 described species. Members are primarily Holarctic in distribution, with notable diversity in Europe, Asia, and North America. Larvae are aquatic and construct portable cases from mineral particles.
Aporus
spider wasps
Aporus is a genus of small spider wasps in the family Pompilidae, containing approximately twelve described species. These wasps are specialized predators that hunt ground-dwelling spiders, particularly those occupying burrows. The genus is distributed across North America, Europe, and Asia. Adults are frequently observed visiting flowers for nectar.
Arachnospila
spider wasps
Arachnospila is a genus of spider wasps (Pompilidae) with a predominantly Holarctic distribution. The genus contains approximately 50 described species organized into five subgenera: Acanthopompilus, Ammosphex, Anoplochares, Arachnospila, and Melanospila. Species occur in open habitats and at forest edges, with nests that may contain multiple cells. The genus has limited representation in montane habitats of the Neotropical and Afrotropical regions.
Aradus lugubris
flat bug
Aradus lugubris is a species of flat bug in the family Aradidae, first described by Fallén in 1807. It is one of the most widely distributed species in its genus, occurring across the Holarctic region in both Europe and North America. The species is known from forest habitats where it lives under the bark of dead trees. Two subspecies are recognized: A. lugubris lugubris and A. lugubris nigricornis.
Araneus yukon
Yukon Orbweaver
Araneus yukon is a species of orb-weaving spider in the family Araneidae. It was described by Herbert W. Levi in 1971. The species is known from boreal and subarctic regions of Russia and Canada, reflecting its tolerance for cold climates. Like other members of the genus Araneus, it constructs spiral orb webs to capture flying insect prey. The specific epithet 'yukon' refers to the Yukon region of northwestern Canada, indicating the type locality or a significant portion of its known range.
Archips
leafroller moths
Archips is a genus of tortricid moths in the tribe Archipini, established by Hübner in 1822. The genus contains numerous leafroller moth species whose larvae feed on a variety of woody plants, including oaks, apples, and baldcypress. Several species are economically significant pests in orchards and forests, with known outbreaks causing defoliation damage. The genus has a complex taxonomic history with multiple synonymized generic names.
Arctacaridae
Arctacaridae is a small family of mites in the order Mesostigmata, discovered and described by Evans in 1955 from arctic regions of North America. The family contains two genera, Arctacarus and Proarctacarus, with six recognized species total. These mites are among the few mesostigmatid lineages specifically adapted to cold, high-latitude environments. The genus Proarctacarus was established in 2003 based on specimens from Canada and the northwestern United States.
Arctia plantaginis
wood tiger, wood tiger moth
Arctia plantaginis, commonly known as the wood tiger moth, is a Holarctic moth species in the family Erebidae. Males exhibit striking color polymorphism with yellow or white hindwing morphs, both featuring black banding patterns that function as aposematic warning signals. The species has been extensively studied as a model organism for understanding the evolutionary trade-offs between predator avoidance, sexual selection, immune function, and thermoregulation. Larvae show predator-induced plasticity in warning signal expression, developing more melanized coloration when exposed to predation risk.
Arctopsyche
Great Gray Spotted Sedges
Arctopsyche is a genus of netspinning caddisflies in the family Hydropsychidae, comprising more than 20 described species. Larvae construct and maintain capture nets throughout the year to filter food from flowing water. The genus exhibits life cycle flexibility, with documented univoltine and semivoltine patterns depending on environmental conditions. Species occur in lotic habitats across the Holarctic region.
Arctosa alpigena
Hilltop Wolf Spider
Arctosa alpigena is a wolf spider in the family Lycosidae with a holarctic distribution spanning North America, Greenland, and Eurasia. It is one of numerous Arctosa species adapted to open, often sandy or gravelly habitats. Like other wolf spiders, it is an active ground-dwelling hunter rather than a web-builder. The species has been subject to reproductive biology studies examining spatial and temporal patterns of mating and offspring production.
Arcynopterygini
springflies
Arcynopterygini is a tribe of springflies (Plecoptera) within the family Perlodidae. The tribe contains approximately 11 genera and more than 30 described species. Members are distributed across the Northern Hemisphere, with genera found in North America, Europe, and Asia. The tribe was established by Ricker & Scudder in 1975.
Argyresthia pygmaeella
Sallow Argent
A small microlepidopteran moth in the family Argyresthiidae, first described from Vienna, Austria in 1775. Adults are active from May to August with a single annual generation. The species is associated with willows, where larvae mine leaf-buds and shoots. It has a broad distribution across Europe, northern Asia, and North America.
Arhopalus rusticus montanus
Arhopalus rusticus montanus is a subspecies of longhorned beetle in the family Cerambycidae, distributed across North America, Europe, and parts of Asia. The species is associated with coniferous forests and develops under the bark of dead or dying conifers. Adults are active during cooler periods, with some populations exhibiting winter activity patterns. This subspecies is part of a complex with Holarctic distribution, showing variation in host preferences across its range.
Arhopalus rusticus obsoletus
Arhopalus rusticus obsoletus is a subspecies of longhorned beetle in the family Cerambycidae. It belongs to a species complex with Holarctic distribution, occurring in both North America and Eurasia. The subspecies is associated with coniferous wood, where larvae develop under bark. Adults are active during warmer months and can be found on or near dead conifers.
Arpedium
Arpedium is a Holarctic genus of rove beetles (Staphylinidae: Omaliinae: Anthophagini) first described by Erichson in 1839. The genus comprises approximately 14 species distributed across the Nearctic and Palaearctic regions, including Europe, Japan, North America, and Central Asia. At least one species, A. cribratum, has been identified as a subnivium specialist—active beneath winter snowpack and rare or inactive during summer. The genus has undergone taxonomic revision, with five new species described recently and several synonymies resolved.
Asagena
Asagena is a genus of cobweb spiders (family Theridiidae) established by Carl Jakob Sundevall in 1833. It comprises nine species distributed across North America, Europe, Asia, and North Africa. Members are small spiders (2.4–5.9 mm body length) that construct webs in sheltered microhabitats including under stones, in leaf litter, under bark, and in moss. The genus was formerly classified within Steatoda.
Asaphidion
Asaphidion is a Holarctic genus of small ground beetles in the family Carabidae. The genus contains approximately 39 species, predominantly distributed across the Palaearctic region with limited representation in North America. Species are characterized by large eyes and diurnal activity patterns. Two native North American species, A. alaskanum and A. yukonense, are restricted to Arctic tundra environments, while the introduced A. curtum has established in the northeastern United States and adjacent Canadian maritime provinces.
Asemum
Asemum is a genus of longhorn beetles (Cerambycidae) in the subfamily Spondylinae, described by Eschscholtz in 1830. Species are primarily associated with coniferous forests and share the pyrophilous (fire-loving) trait of seeking out burned or fire-killed trees. The genus has a Holarctic distribution, with notable range expansion documented for A. tenuicorne into northern Europe. A. striatum, the type species, is among the most widespread and serves as host for specialized tylenchid nematode parasites.
Aspicerinae
Aspicerinae is a subfamily of parasitic cynipoid wasps within the family Figitidae (Hymenoptera: Cynipoidea). The subfamily contains multiple genera including Aspicera, Prosaspicera, Callaspidia, Omalaspis, and Paraspicera. Members are primarily Holarctic in distribution, though some genera extend into the Neotropical, Afrotropical, and Oriental regions. The group has undergone extensive recent taxonomic revision, revealing substantially greater species diversity than previously recognized.
Atomaria apicalis
silken fungus beetle
Atomaria apicalis is a species of silken fungus beetle in the family Cryptophagidae. It has a Holarctic distribution, occurring in Europe, Northern Asia (excluding China), and North America. The species is one of many small beetles in the genus Atomaria that are associated with fungal habitats.
Atomaria wollastoni
silken fungus beetle
Atomaria wollastoni is a species of silken fungus beetle in the family Cryptophagidae, a group of small beetles associated with fungal substrates. The species has a Holarctic distribution, occurring in Europe, Northern Asia (excluding China), and North America. Like other members of its family, it is presumed to inhabit decaying organic matter and fungal environments, though specific ecological details remain poorly documented.
Atomoscelis onustus
Atomoscelis onustus is a species of plant bug in the family Miridae. It exhibits a broad Holarctic distribution spanning the Palearctic and Nearctic regions. The species has been documented across diverse environments from the western Mediterranean and Middle East to western North America. Like other members of the genus, it is presumed to be phytophagous, though specific host plant associations remain poorly documented.
Attulus finschi
Attulus finschi is a species of jumping spider in the family Salticidae. It occurs across northern regions of North America and Eurasia, with documented populations in Russia (from West Siberia to the Far East), Canada, and the United States. As a member of the Attulus genus, it shares the characteristic jumping ability and visual acuity typical of salticid spiders.
Attulus floricola
Flower Jumping Spider
Attulus floricola is a small jumping spider in the family Salticidae with a widespread Holarctic distribution spanning Europe, Asia, and North America. Originally described as Euophrys floricola in 1837, the species has undergone extensive taxonomic revision, with North American populations formerly recognized as separate species or subspecies before being synonymized in 2020. The species name refers to its habit of living on flower heads and similar vegetation. It inhabits wetland habitats including bogs, marshes, fens, and meadows.
Atylotus hyalicosta
Atylotus hyalicosta is a species of horse fly (family Tabanidae) described by Teskey in 1984. It belongs to the genus Atylotus, a group of biting flies known for their robust build and large eyes. Like other members of Tabanidae, females of this species likely require blood meals for egg development, while males feed on nectar and other sugar sources. The species is poorly documented in public literature, with only one observation recorded on iNaturalist.
Aulagromyza
Aulagromyza is a genus of leaf-miner flies in the family Agromyzidae, comprising approximately 50 described species distributed across the Holarctic region. Species in this genus are primarily phytophagous, with larvae that feed internally within leaf parenchyma, creating distinctive blotch or serpentine mines. Several species are monophagous or oligophagous, showing strong host associations with particular plant genera including Fraxinus (ash), Lonicera (honeysuckle), and Populus (poplar). The genus is of ecological interest due to its role in leaf herbivory and its interactions with parasitoid wasps.
Axymyiidae
A small family of nematoceran flies comprising four extant genera and nine described species, with eight additional fossil species. Axymyiidae is the sole member of the infraorder Axymyiomorpha, though historically classified within Bibionomorpha. The family is distributed across the Holarctic and Oriental regions. Larvae are xylophilic and semi-aquatic, developing in saturated decaying wood.
Baccha
Baccha is a genus of hoverflies in the subfamily Syrphinae, characterized by extremely slender, club-shaped abdomens. Adults range from 7 to 10 mm in length and exhibit wasp-like body proportions with clear or faintly marked wings. The genus is distinguished by its distinctive elongate body form among syrphine flies.