Holarctic
Guides
Protophormia terraenovae
northern blowfly, blue-bottle fly, blue-assed fly, blackbottle
Protophormia terraenovae is a large, metallic blue-green blowfly with a Holarctic distribution. It is the most cold-tolerant calliphorid species, occurring from the Arctic to temperate regions. The species is economically significant as a cause of myiasis in livestock and valuable in maggot debridement therapy due to its selective consumption of necrotic tissue and antibiotic secretions. Its temperature-dependent development makes it a key forensic indicator for post-mortem interval estimation.
Psallus
Psallus is a genus of plant bugs in the family Miridae, subfamily Phylinae, comprising over 160 described species. The genus is predominantly Palearctic in distribution, with some species demonstrating Holarctic ranges and several having been introduced to the Nearctic region. Species are generally small, often measuring under 4 mm, with many exhibiting reddish or orange coloration. Host plant associations have been documented for several species, primarily with woody plants including oaks (Quercus), willows (Salix), and birch (Betula).
Psammotettix beirnei
Psammotettix beirnei is a leafhopper species in the family Cicadellidae, described by Greene in 1971. It belongs to the genus Psammotettix, which comprises small, grass-associated leafhoppers. The species is recorded from Canada, consistent with the genus's generally Holarctic distribution.
Psammotettix lividellus
Psammotettix lividellus is a leafhopper species in the family Cicadellidae, subfamily Deltocephalinae. It belongs to a genus associated with sandy or psammophilous habitats. The species has been recorded across northern North America including Alaska, western Canada, and the northern United States. It is one of approximately 40 species in the genus Psammotettix, which is distributed across the Holarctic region.
Psen
Psen is a genus of aphid wasps comprising at least 90 described species. These solitary wasps are placed in the family Crabronidae (subfamily Pemphredoninae, tribe Psenini) and are characterized by their specialized predation on aphids. The genus was established by Latreille in 1796 and has a primarily Holarctic distribution.
Pseudotelphusa
Pseudotelphusa is a genus of small moths in the family Gelechiidae, established by Janse in 1958. The genus contains approximately 30 described species distributed primarily across the Northern Hemisphere, with records from Europe, North America, and parts of Asia. Species in this genus are generally small with wingspans typical of gelechiid moths. The genus includes both day-flying and nocturnal species, with some exhibiting characteristic wing patterns of pale ground color with darker markings.
Psilidae
rust flies
Psilidae is a family of small to medium-sized flies commonly called rust flies, with at least 38 species in four genera. The family is well represented in temperate zones and is found mainly in the Holarctic region. The carrot fly (Chamaepsila rosae) is the most economically significant member, a major agricultural pest of carrots and related crops. Larvae are phytophagous, feeding in stems, tubers, or roots of nonwoody plants.
Pterostichus
Blackclock Ground Beetles
Pterostichus is a large genus of ground beetles (Carabidae) in the subfamily Harpalinae, comprising over 1,200 species with a Holarctic distribution. These beetles are primarily predatory and are commonly found in ground-level habitats, often beneath rocks and debris. The genus exhibits considerable ecological diversity, with species showing varied substrate preferences ranging from sandy soils to subterranean environments.
Pterostichus adstrictus
Upland Blackclock
Pterostichus adstrictus is a cold-adapted ground beetle with a Holarctic-circumpolar distribution, occurring across subarctic and alpine regions of North America and Eurasia. In North America it ranges from the Bering Sea coast to Newfoundland and south to Pennsylvania, Indiana, South Dakota, New Mexico, and California's Sierra Nevada. European populations were historically known only from northern peripheries (Northern Ireland, Wales, Scandinavia) until discovery in the Austrian Alps, representing a glacial relict with arctic-alpine distribution. The species exhibits stenotopic habitat specificity and has been observed to form locally dense populations despite restricted geographic occurrence.
Pterostichus agonus
Pterostichus agonus is a species of ground beetle in the family Carabidae, first described by G.H. Horn in 1880. The species exhibits a Holarctic distribution, occurring across Europe, Northern Asia (excluding China), and North America. Two subspecies are recognized: P. a. agonus and P. a. averenskii. As a member of the genus Pterostichus, it belongs to a diverse group of woodland ground beetles characterized by their elongated body form and predatory habits.
Pterostichus costatus
Pterostichus costatus is a woodland ground beetle in the family Carabidae. It occurs across a broad holarctic distribution spanning Europe, Northern Asia (excluding China), and North America. The species inhabits forested environments and is part of a large genus of ground beetles characterized by relatively robust body forms.
Pterostichus empetricola
Pterostichus empetricola is a species of woodland ground beetle in the family Carabidae. It is distributed across the Holarctic region, with records from Europe, Northern Asia (excluding China), and North America including Alaska, Canada, and the United States. The species is part of the diverse genus Pterostichus, which contains numerous ground beetle species.
Pterostichus parasimilis
Pterostichus parasimilis is a species of woodland ground beetle in the family Carabidae, described by Ball in 1962. It is distributed across the Holarctic region, with records from Alaska, Canada, Russia, and the United States. Like other members of the genus Pterostichus, it is a ground-dwelling beetle typically associated with forest floor habitats.
Pterostichus pinguedineus
Pterostichus pinguedineus is a species of ground beetle in the family Carabidae, described by Eschscholtz in 1823. It belongs to the genus Pterostichus, one of the largest genera of carabid beetles. The species has a Holarctic distribution, occurring across northern regions of North America, Europe, and Northern Asia.
Pterostichus similis
Pterostichus similis is a species of woodland ground beetle in the family Carabidae. It occurs across a broad Holarctic distribution, spanning Europe, Northern Asia (excluding China), and North America. The species inhabits woodland environments and is part of the diverse Pterostichus genus, one of the largest genera of ground beetles.
Pterostichus strenuus
Rough-chested Blackclock
Pterostichus strenuus is a woodland ground beetle in the family Carabidae. The species has a Holarctic distribution, occurring in North America, Europe, and temperate Asia. It is one of many Pterostichus species adapted to forest floor habitats. Taxonomic authorities vary, with some sources listing Erichson (1837) and others Panzer (1796) or LeConte (1853).
Pterostichus vermiculosus
Pterostichus vermiculosus is a ground beetle species in the family Carabidae with a Holarctic distribution spanning Europe, Northern Asia, and North America. In Russia, it has been documented in tundra habitats including lichen moss tundra, shrub tundra, and tundra lowlands. The species was described by Ménétriés in 1851.
Ptychoptera
phantom crane flies
Ptychoptera is a genus of phantom crane flies comprising at least 70 described species. The genus is characterized by larvae that are aquatic or semi-aquatic detritivores inhabiting freshwater environments. Adults are recognized by their distinctive wing folding behavior, giving rise to the common name "fold-winged crane flies." Species occur across the Holarctic and Oriental regions, with significant diversity in China.
Pyla fusca
Speckled Black Pyla Moth
Pyla fusca is a snout moth in the subfamily Phycitinae with a Holarctic distribution. It is the only member of its genus found outside North America, making it taxonomically distinctive. The species is associated with heathland habitats, particularly areas of burnt heath where its dark coloration provides camouflage. Adults are active during summer months, and larvae feed on Ericaceae plants.
Pyrgus
Grizzled Skippers, Checkered Skippers
Pyrgus is a genus of skippers in the family Hesperiidae, commonly known as grizzled skippers. The genus occurs primarily in the Holarctic region, with some species extending into the Neotropics. Following a major taxonomic revision in 2019, most New World species were moved to other genera (Burnsius, Chirgus, Heliopetes), leaving only four Pyrgus species in the Americas: P. centaureae, P. ruralis, P. scriptura, and P. xanthus. The genus is characterized by small butterflies with checkered or grizzled wing patterns.
Pytho
dead log beetles, dead log bark beetles
Pytho is a small genus of saproxylic beetles in the family Pythidae, commonly known as dead log beetles or dead log bark beetles. The genus comprises approximately nine to ten described species distributed across the Holarctic region, recognized as typically boreal taxa. Species inhabit the cambial layer of dead trees, particularly conifers, where larvae feed on partially decomposed wood and bark. Several species have disjunct distributions spanning North America, Europe, and Japan, reflecting complex historical biogeographic patterns involving vicariance and dispersal across Beringia. Some species, such as P. abieticola, are considered relicts of primeval forests and are in decline across much of Central Europe.
Quedius fellmani
Quedius fellmani is a rove beetle in the family Staphylinidae. It is a Holarctic species with a broad distribution spanning northern and central Europe, Russia across multiple regions including Siberia and the Far East, Mongolia, Greenland, and North America from Alaska through Canada to Colorado and New Hampshire. The species was described by Zetterstedt in 1838.
Quedius fulvicollis
Quedius fulvicollis is a rove beetle (family Staphylinidae) described by Stephens in 1833. Originally placed in the genus Raphirus, it is now classified within the large genus Quedius. The species has a Holarctic distribution, occurring across Europe, Russia, Central Asia, Iceland, and North America. As a member of Staphylininae, it likely occupies ground-dwelling habitats and contributes to decomposition processes, though specific ecological studies are limited.
Quedius molochinus
Quedius molochinus is a large, robust rove beetle in the subgenus Quedius sensu stricto. It is one of the most widespread species in its genus across the Palearctic region. The species has been introduced to eastern Canada, likely through historical ship ballast transport. Recent molecular studies have revealed unexpected cryptic diversity within this morphologically uniform species.
Quedius sublimbatus
Quedius sublimbatus is a rove beetle (Staphylinidae) with a Holarctic distribution spanning northern Eurasia and North America. The species was described by Mäklin in 1853 and is currently classified within the subgenus Raphirus of the genus Quedius. It inhabits boreal and subarctic regions across a broad longitudinal range.
Rabdophaga
Willow Gall Midges
Rabdophaga is a genus of gall midges in the family Cecidomyiidae comprising approximately 105 species distributed across Africa, Asia, Europe, and North America. The genus is predominantly associated with willows (Salix spp.), where larvae induce characteristic galls; most species are host-specific to particular willow species or sections. A notable exception is R. giraudiana, which forms stem galls on poplars (Populus spp.), and a 2016 record documents the first Rabdophaga species on a non-Salicaceae host, Symplocos cochinchinensis (Symplocaceae). Species within the genus exhibit varying degrees of host fidelity, with some showing strong preference-performance relationships and others demonstrating broader host ranges across willow sections.
Raphidiidae
Raphidiid Snakeflies, Snakeflies
Raphidiidae is the largest family of snakeflies in the order Raphidioptera, comprising over 200 extant species. Members are characterized by an elongated prothorax that gives them a distinctive 'snake-like' appearance. The family is distributed across the Northern Hemisphere, with notable diversity in North America, Europe, and Asia. The genus Alena is considered the most morphologically distinct within the family due to unusual male genital sclerites. Snakeflies in this family are predators of small arthropods.
Recurvaria
Recurvaria is a genus of small moths in the family Gelechiidae, established by Haworth in 1828. The genus contains approximately 40 described species distributed across the Holarctic region. Several species are economically significant as pests of coniferous trees and pistachio, with larvae that mine needles or feed internally within fruits. The genus exhibits diverse life history strategies, including univoltine and bivoltine cycles, with some species requiring two years to complete development.
Reduvius personatus
Masked Hunter
Reduvius personatus, commonly known as the masked hunter, is a cosmopolitan assassin bug recognized for the distinctive debris-camouflaged appearance of its nymphs. The species is a generalist predator of small arthropods and has been introduced to multiple continents through human activity. Adults are uniformly dark brown to black, winged insects measuring 17–22 mm, while nymphs appear gray or light-colored due to accumulated dust and lint on their bodies. Though beneficial as predators of household pests like bed bugs, they can deliver a painful defensive bite when mishandled.
Resapamea
Resapamea is a genus of noctuid moths established by Varga & Ronkay in 1992. The genus comprises approximately 14 described species distributed across the Holarctic region. Many species were transferred from other genera, particularly Luperina, based on revised morphological and phylogenetic studies. The genus includes both widespread species and geographically restricted endemics in high-altitude and northern habitats.
Rhadiurgus
Rhadiurgus is a genus of robber flies (Asilidae) established by Loew in 1849. The genus contains at least one confirmed species, Rhadiurgus variabilis, which occurs in the Holarctic region. Members of this genus are predatory dipterans that hunt other insects in flight.
Rhadiurgus variabilis
Rhadiurgus variabilis is a Holarctic robber fly in the family Asilidae. The species was originally described as Asilus variabilis by Zetterstedt in 1838. Records indicate presence in northwestern Europe including Belgium, Denmark, Norway, and Sweden.
Rhagiini
Rhagiini is a tribe of longhorn beetles within the subfamily Lepturinae. Members are characterized by elongated bodies and flower-visiting behavior. The tribe occurs primarily in the Northern Hemisphere with substantial diversity in North America and Eurasia.
Rhagium
flower longhorn beetles, ribbed pine borers
Rhagium is a genus of flower longhorn beetles in the subfamily Lepturinae, family Cerambycidae. The genus contains approximately 25 described species distributed across the Holarctic region, with notable species including the widespread Rhagium inquisitor (ribbed pine borer) and Rhagium mordax. Species in this genus exhibit distinctive morphological features including relatively short antennae compared to other cerambycids, often with ribbed or sculptured elytra. The genus is notable for containing the only North American cerambycid known to overwinter as adults (R. inquisitor).
Rhagium inquisitor
Ribbed Pine Borer
Rhagium inquisitor, commonly known as the ribbed pine borer, is a medium-sized longhorn beetle distinguished by its unusual morphology and unique life history. Unlike most cerambycids, adults have short antennae and a 'big-shouldered' build with heavily ribbed elytra. The species is notable for being one of the few North American cerambycids to overwinter as adults rather than larvae, and for pupating directly beneath bark rather than in the sapwood. It has a broad Holarctic distribution spanning North America, Europe, and Asia.
Rhagoletis
fruit flies
Rhagoletis is a genus of tephritid fruit flies comprising approximately 70–100 species. The genus name derives from Ancient Greek *rhago* (a kind of spider), possibly referencing the jumping spider mimicry observed in at least *R. pomonella*. Species are primarily phytophagous, with larvae developing in fruits of specific host plants. Several species are significant agricultural pests, including the apple maggot (*R. pomonella*), blueberry maggot (*R. mendax*), and cherry fruit flies (*R. cingulata*, *R. cerasi*). The genus exhibits strong host specialization, with females showing preference for ovipositing in the host fruit where they developed.
Rhantus sericans
Rhantus sericans is a predaceous diving beetle in the family Dytiscidae, first described by Sharp in 1882. The species is distributed across North America and has been recorded from the Holarctic region, including the Canadian province of Alberta. As a member of the genus Rhantus, it belongs to a group of diving beetles adapted to aquatic environments. The species is represented by 88 observations on iNaturalist, indicating it is documented but not exceptionally common in citizen science records.
Rhantus suturellus
Rhantus suturellus is a predaceous diving beetle in the family Dytiscidae. It is distributed across the Holarctic region, occurring in both North America and the Palearctic. The species is part of a genus of aquatic beetles adapted to freshwater environments.
Rhegmoclematini
Rhegmoclematini is a tribe of minute black scavenger flies (family Scatopsidae) within the subfamily Scatopsinae. These flies are small-bodied dipterans associated with decaying organic matter. The tribe is distinguished by morphological features of the male genitalia, particularly the structure of the claspers. Members are poorly known compared to the related tribe Scatopsini, with limited biological data available.
Rhithrogena
March Browns, Olive Uprights
Rhithrogena is a genus of flatheaded mayflies in the family Heptageniidae, commonly known as March Browns or Olive Uprights. The genus contains approximately 153 species distributed across the Holarctic region. Larvae are primarily scrapers that feed on periphyton from stones in running waters. Several species serve as important food sources for fish and have been studied for their bioindicator potential in freshwater monitoring.
Rhopalopterum
frit flies
Rhopalopterum is a genus of small frit flies in the family Chloropidae, established by Duda in 1929. The genus contains approximately 10 described species distributed primarily in the Holarctic region. Species within this genus are morphologically similar to other chloropids, with most described during the late 19th and early 20th centuries. The genus is taxonomically placed within the subfamily Oscinellinae and tribe Oscinisomatini.
Rhoptromeris
Rhoptromeris is a genus of small parasitoid wasps in the family Figitidae (subfamily Eucoilinae). Species in this genus develop as parasitoids of chloropid flies (Diptera: Chloropidae), with hosts typically inhabiting conifer cones or grass stems. The genus currently contains nine valid Holarctic species, including the type species R. heptoma, which is an important parasitoid of the frit fly Oscinella frit, a significant pest of cereal crops.
Rhysodromus alascensis
Rhysodromus alascensis is a species of running crab spider in the family Philodromidae. It has a broad transcontinental distribution spanning northern North America and Eurasia, including Alaska, Siberia, Kazakhstan, and China. The species was originally described as Philodromus alascensis by Keyserling in 1884 and later transferred to the genus Rhysodromus. Like other philodromids, it is an active hunter that does not build webs to capture prey.
Rhyssella
Rhyssella is a genus of ichneumon wasps in the family Ichneumonidae, containing approximately 10 described species. The genus was established by Rohwer in 1920. Species in this genus are parasitoids of wood-boring insects, with documented associations to wood-wasps in the genus Xiphydria. The genus has a Holarctic distribution, with records from North America, Europe, and Asia.
Robertus
Robertus is a genus of comb-footed spiders in the family Theridiidae. It was established by Octavius Pickard-Cambridge in 1879 and is recognized as the senior synonym of the former genus Garritus. The genus comprises small spiders that construct tangled, irregular webs. Species within Robertus are found primarily in the Northern Hemisphere, with documented occurrences in Europe and North America.
Saldula opacula
shore bug
Saldula opacula is a species of shore bug in the family Saldidae, first described by Zetterstedt in 1838. It belongs to the genus Saldula, which comprises small predatory true bugs commonly found in moist habitats near water bodies. The species has a broad distribution spanning multiple continents, with confirmed records from Europe, Northern Asia, and North America. Like other members of the family Saldidae, it is adapted to shoreline environments where it hunts small invertebrate prey.
Saldula saltatoria
Common Shore Bug
Saldula saltatoria is a Holarctic shore bug with circumboreal distribution, widespread across central Europe and often occurring in large numbers. It is an active predator of small invertebrates inhabiting diverse shoreline habitats. The species shows remarkable ecological flexibility, occurring from small water bodies to large lakes and rivers, and from sea level to over 2000 meters elevation in alpine regions.
Salticus
Zebra spiders, Jumping spiders
Salticus is a genus of jumping spiders (Salticidae), the type genus for the family. Species range from 3–7 mm in body length and are distinguished by coloration produced by specialized scales covering a dark integument. Several common species exhibit transverse black-and-white striping that gives the group its "zebra spider" common name, though some species display iridescent or red-and-white patterns instead. The genus has been recorded on every continent except Antarctica, with highest diversity in the southwestern United States, Mexico, and the Mediterranean region.
Saperda
flat-faced longhorn beetles
Saperda is a genus of flat-faced longhorn beetles in the family Cerambycidae, subfamily Lamiinae, erected by Johan Christian Fabricius in 1775. Species in this genus are wood-boring beetles whose larvae develop in living or stressed trees, particularly poplars, willows, and other broadleaf hosts. Several species are economically significant pests of plantation trees and fruit crops. The genus has a Holarctic distribution with highest diversity in the Palearctic region.
Sapromyza
Sapromyza is a genus of small flies in the family Lauxaniidae, containing at least 330 described species. The genus has a broad distribution across the Holarctic region and beyond, with documented records from Europe, the Middle East, and North America. Taxonomic revisions have focused on regional species inventories and identification keys, particularly in understudied areas such as Israel and Iran.