Introduced-species
Guides
Aphodius pedellus
Aphodius pedellus is a small dung beetle native to Europe that has been introduced to North America, where it is now widespread and common in cattle pastures. It was long confused with Aphodius fimetarius as part of a species complex, but morphological and DNA barcoding studies have confirmed them as distinct species. In Canada, only A. pedellus is present; A. fimetarius is absent. North American populations show reduced genetic diversity consistent with introduction during European settlement.
Aphrophora alni
European alder spittle bug, alder spittlebug
Aphrophora alni is a froghopper in the family Aphrophoridae, commonly known as the European alder spittlebug. It is the most common and widespread of the four Aphrophora species in the UK and one of the larger froghoppers in its range. Adults are distinguished by a pale median keel on the head and pronotum, dark brown coloration, and two pale patches along the costal margin of the forewings. The species is polyphagous, feeding on deciduous trees as adults and herbaceous plants as larvae. Nymphs produce characteristic foam nests ('cuckoo spit') with adhesive properties of biotechnological interest. It has been recorded as a pest on alder and is a potential vector of the bacterial plant pathogen Xylella fastidiosa.
Appendiseta
Appendiseta is a monotypic genus of aphids in the family Aphididae, established by Richards in 1965. The sole described species, Appendiseta robiniae, is known as the black locust aphid and has been introduced to Europe from its native North American range. The genus is classified within the tribe Therioaphidini and subfamily Calaphidinae.
Apterona helicoidella
snailcase bagworm
A bagworm moth native to Europe that constructs a distinctive helical, snail-like case. The species was accidentally introduced to North America in the 1940s and has since established populations across multiple U.S. regions. Adults are reduced or absent in females, which retain a larval form and remain within their cases.
Araneus diadematus
European garden spider, cross orbweaver, diadem spider, cross spider, crowned orb weaver, pumpkin spider
Araneus diadematus is a medium-sized orb-weaving spider native to Europe, now naturalized across North America. Adult females reach 6.5–20 mm in body length, males 5.5–13 mm. The species is named for the distinctive white cross-shaped pattern on its dorsal abdomen, formed by guanine deposits. It constructs classic spiral orb webs with 25–30 radial threads at approximately 15° angles, often positioned in gardens, porches, and other human-modified habitats. The spider is diurnal, typically hanging head-down at the web hub, and exhibits a defensive vibrating behavior when disturbed.
Archips fuscocupreanus
exotic leafroller moth, apple tortrix
Archips fuscocupreanus is a leafroller moth in the family Tortricidae, native to East Asia (China, South Korea, Japan, and eastern Russia). It is an introduced species in the northeastern United States, where it has established populations in Connecticut, Massachusetts, New Jersey, New York, Rhode Island, and Washington. The species is a generalist herbivore with larvae feeding on numerous woody and herbaceous plants across multiple families. Adults are active in summer, with flight periods recorded from June to July in China.
Archips podana
Large Fruit-tree Tortrix
Archips podana is a leafroller moth in the family Tortricidae, first described by Scopoli in 1763. It is notable for exhibiting polymorphism in male genitalia, with four distinct morphs differing in the presence or absence of apical and/or lateral prongs on the phallus. The species is widely distributed across Europe and Asia, and has been introduced to North America. Larvae are polyphagous herbivores on deciduous trees and shrubs, with significant economic impact on fruit crops including apple and pear.
Arctosa perita
Sand Bear Spider
Arctosa perita is a wolf spider in the family Lycosidae, commonly known as the sand bear spider. It is native to Europe, North Africa, Turkey, the Caucasus, and Russia, and has been introduced to Canada. The species is adapted to dry, sandy habitats where it constructs burrows.
Arge ochropus
rose sawfly
Arge ochropus, commonly known as the rose sawfly, is a small sawfly species in the family Argidae. Adults measure 7–10 mm in length and are active primarily in spring. The species is native to the Palearctic region and has been introduced to northeastern North America. Larvae feed on rose leaves, causing skeletonization damage, while adults consume nectar and pollen from several flowering plants. The species produces two generations annually in temperate regions.
Argyresthia cupressella
cypress tip moth
Argyresthia cupressella, commonly known as the cypress tip moth, is a small microlepidopteran moth in the family Argyresthiidae. Native to the western coast of North America, it has been introduced to Europe where established populations now occur. The species is recognized as a pest of ornamental and forest conifers due to larval feeding damage.
Argyresthia thuiella
arborvitae leafminer, thuja mining moth, American thuja shoot moth
Argyresthia thuiella is a micro-moth in the family Argyresthiidae, commonly known as the arborvitae leafminer. Native to North America, it has been introduced to Europe multiple times since 1971. The species develops one generation annually, with larvae mining the foliage and twigs of Thuja and Chamaecyparis species. Adults are active from May to July and have a wingspan of approximately 8 mm.
Argyrodes nephilae
dewdrop spider
Argyrodes nephilae is a small cobweb spider in the family Theridiidae, commonly known as a dewdrop spider. It lives as a kleptoparasite in the webs of large orb-weaving spiders, particularly those in the genus Nephila. The species ranges from the United States through Central and South America to Argentina and the Galapagos Islands, with introduced populations in India.
Aristotelia ivae
Aristotelia ivae is a small moth in the family Gelechiidae, described by August Busck in 1900. It is native to the southeastern United States, with confirmed records from Florida and Georgia. The species was introduced to Australia in 1969 as a biological control agent for the invasive weed Baccharis halimifolia. Its larvae feed specifically on Iva frutescens in its native range.
Armadillidiidae
pill bugs, roly polies, pill woodlice, slaters, potato bugs, curly bugs, doodle bugs, Butchy-Boys
Armadillidiidae is a family of terrestrial isopod crustaceans distinguished by their ability to roll into a complete ball (conglobation) when disturbed. This defensive behavior, shared with unrelated pill millipedes and some other arthropods, has made them commonly known as pill bugs or roly polies. The family contains approximately 18 recognized genera and shows highest diversity in Mediterranean karstic regions, with some species having achieved widespread global distribution through human activity.
Armadillidium nasatum
Nosy Pill Woodlouse
Armadillidium nasatum is a large woodlouse species native to Western Europe, particularly Britain, that has been introduced to North America and other regions. It reaches up to 21 mm in length and is distinguished from congeners by a rectangular protrusion ("nose") at the apex of the head and a rounded tail tip with incurved sides. Unlike some relatives, it does not form a complete ball when enrolled. The species exhibits synanthropic tendencies and prefers drier habitats than most woodlice.
Artema
Giant Cellar Spiders
Artema is a genus of cellar spiders (family Pholcidae) first described by Charles Athanase Walckenaer in 1837. The genus includes some of the largest pholcid spiders and is primarily distributed from West Africa through Central Asia to Pakistan. One species, A. atlanta, has been introduced worldwide. The genus comprises twelve recognized species as of October 2025.
Asciodema obsoleta
Asciodema obsoleta is a Palearctic true bug in the family Miridae. The species has been recorded across parts of Europe, North Africa, and has been introduced to North America. It belongs to the plant bug family Miridae, one of the largest families of true bugs with predominantly phytophagous feeding habits.
Ataenius gracilis
Slender Small Dung Beetle
Ataenius gracilis is a small aphodiine dung beetle in the family Scarabaeidae. It is native to the Americas but has been introduced to Europe and Oceania, including the Azores and Galápagos Islands. The species has been recorded from diverse habitats ranging from the Nearctic zone through the Neotropics.
Ateuchus lecontei
Ateuchus lecontei is a dung beetle species in the family Scarabaeidae, described by Harold in 1868. The species is native to the Nearctic region, with records from the eastern and southeastern United States. It has been introduced to Hawaii and other Oceania locations. Very few documented observations exist, with only 14 records on iNaturalist.
Atheta longicornis
Atheta longicornis is a rove beetle species in the family Staphylinidae, first described by Gravenhorst in 1802. The species has a broad native distribution across Europe, North Africa, and parts of Asia, and has been introduced to North America (Canada and the United States), Australia, and other regions. As a member of the hyperdiverse genus Atheta, it inhabits various terrestrial habitats where it contributes to decomposition processes. The species is characterized by its relatively long antennae, which inspired its specific epithet.
Attulus ammophilus
Attulus ammophilus is a jumping spider species in the family Salticidae, first described by Thorell in 1875. It is native to parts of Europe, Northern Asia, and Central Asia, with introduced populations established in North America. The species name 'ammophilus' suggests an association with sandy habitats. Unlike the closely related and Critically Endangered Attulus distinguendus, this species has a broader distribution and is not considered threatened.
Attulus fasciger
Asiatic Wall Jumping Spider
Attulus fasciger is a small jumping spider native to northern and western Asia, introduced to North America in the mid-20th century. It measures 3–4 mm and exhibits brownish-black coloration with mottled brown-and-grey patterning. The species has successfully established in human-modified environments, particularly on man-made structures where artificial lighting extends its foraging opportunities. Males are distinguished from females by a more slender abdomen and enlarged black palps.
Atypidae
purseweb spiders, atypical tarantulas
Atypidae is a family of mygalomorph spiders commonly known as purseweb spiders or atypical tarantulas. The family contains only three genera and represents one of the most archaic spider lineages. Members are obligate burrowers that construct distinctive sock-like, silken tubes extending from underground burrows up vertical surfaces. They are ambush predators that rarely leave their retreats, instead detecting and capturing prey from within their webs. The family has a disjunct distribution across Eurasia, northern Africa, and North America, with most species in the genus Atypus.
Atypus
Purse-web Spider, Purseweb Spider
Atypus is a genus of mygalomorph spiders commonly known as purse-web spiders, first described by Latreille in 1804. These spiders construct distinctive silk tubes (purse-webs) that extend from underground burrows vertically along tree bases, fences, or other surfaces. The genus occurs across Eurasia and northern Africa, with 38 described species as of 2025. Atypus species are perennial, with females living 8–10 years, and conduct nearly all life activities—including predation, mating, and egg-laying—within their sealed webs. One Asian species, A. karschi, has been introduced and established in southeastern Pennsylvania, USA.
Atypus karschi
Karsch's Purseweb Spider
Atypus karschi is a mygalomorph spider native to East Asia (Korea, China, Taiwan, Japan) that has been introduced and established in southeastern Pennsylvania, USA. It constructs distinctive camouflaged tubular purse-webs attached to trees, shrubs, or walls, with a portion buried underground. The species was previously misidentified in North America as A. snetsingeri, but genetic analysis confirmed conspecificity with Asian populations. It is the first documented case of an introduced purse-web spider.
Aulacobaris lepidii
Imported Crucifer Weevil
Aulacobaris lepidii, commonly known as the Imported Crucifer Weevil, is a small weevil species in the family Curculionidae. It has been introduced to North America from Europe and is associated with plants in the mustard family (Brassicaceae). The species is part of a genus whose members are often recognized as seed-feeding weevils of economic concern.
Auplopus carbonarius
potter spider wasp, yellow-faced spider wasp
Auplopus carbonarius is a small spider wasp native to Europe that has been introduced to North America. Females construct distinctive barrel-shaped mud cells inside pre-existing cavities, stocking each with a paralyzed spider as food for their larva. The species is notable for its complex nesting behavior among Pompilidae, including leg amputation of prey to facilitate transport. Adults are approximately 10 mm in length, with males distinguished by ivory-colored maculae beside the eyes.
Autalia puncticollis
Autalia puncticollis is a rove beetle species in the family Staphylinidae, described by Sharp in 1864. It belongs to the tribe Autaliini within the subfamily Aleocharinae. The species has a Palearctic native distribution across Europe, Russia, Turkey, and Japan, with introduced populations in western North America including British Columbia, California, and Washington.
Autosticha kyotensis
Kyoto moth
A small moth in the family Autostichidae, originally described from Japan in 1931. It has established populations in the southeastern United States as an introduced species. The species is known to feed on specific host plants in both its native and introduced ranges.
Axinotarsus pulicarius
soft-winged flower beetle
A small soft-winged flower beetle (Melyridae) measuring 2.75–3.75 mm, distinguished by a reddish-yellow pronotum with a broad black median band contrasting with dark grey to nearly black head and elytra. Native to Europe with broad distribution excluding northern latitudes and southern Mediterranean regions; introduced to North America where established in the Pacific Northwest and Great Lakes region. Known for elaborate courtship involving excitatory gland displays and mutual frontal tapping between sexes.
Balclutha
Balclutha is a large genus of leafhoppers in the family Cicadellidae, with over 100 species and a cosmopolitan distribution. The genus is named after Balclutha, Scotland. These small insects are primarily associated with grasses and sedges (Poaceae), and several species have become economically significant as pests of cereal crops, particularly rice. Some species are known vectors of plant pathogens, including phytoplasmas affecting grapevine and other crops. The genus includes both native and introduced species, with several documented cases of recent range expansion through international trade.
Balclutha jafara
Balclutha jafara is a leafhopper species native to Africa that was introduced to the Western Hemisphere by 2019. First detected in southern Florida in 2020 and in Colombian shipments entering the United States in 2019, it was previously known only from the Seychelles and Aldabra Islands. The species has since been documented across a broader African range including Kenya, South Africa, South Sudan, Zambia, and Zimbabwe. Molecular analysis using COI barcodes confirmed its identity and revealed connections between populations on multiple continents.
Barynotus obscurus
Ground Weevil
Barynotus obscurus is a species of weevil in the family Curculionidae, native to Europe. The species has been introduced to North America, with established populations in British Columbia, New Brunswick, and other regions. It is commonly known as the Ground Weevil.
Barypeithes pellucidus
Barypeithes pellucidus is a European weevil species in the family Curculionidae. It has been introduced to North America, where it has been established in hardwood forests for over a century. The species is currently recognized as a synonym of Exomias pellucidus in some taxonomic databases.
Bathyplectes
Bathyplectes is a genus of ichneumonid wasps (Hymenoptera: Ichneumonidae: Campopleginae) comprising larval parasitoids of weevil pests, particularly the alfalfa weevil (Hypera postica). The genus includes multiple Palaearctic species, with B. curculionis and B. anura being the most studied for biological control of alfalfa weevil in agricultural systems. These parasitoids have been introduced to North America as part of classical biological control programs. A distinctive behavioral trait occurs in B. anura, whose cocooned larvae jump up to 5 cm to locate favorable microhabitats.
Bathyplectes infernalis
Bathyplectes infernalis is a parasitoid wasp in the family Ichneumonidae. It is a biological control agent of the alfalfa weevil (Hypera postica), a major agricultural pest in western North America. The species has been introduced and released in the United States as part of classical biological control programs. It is one of several Bathyplectes species used to manage weevil populations in alfalfa fields.
Batrachedra pinicolella
Pine Cosmet
A small conifer-feeding moth in the family Batrachedridae. Formerly cryptic within a species complex, integrative taxonomic studies using DNA barcoding, nuclear markers, and ddRAD sequencing distinguished it from the newly described B. confusella. It has a boreo-montane distribution pattern and is associated primarily with Norway spruce.
Belonuchus rufipennis
Belonuchus rufipennis is a species of rove beetle (family Staphylinidae) first described by Fabricius in 1801. It is considered a relatively large species within the rove beetle family, with documented body lengths ranging from 4.6 to 9 mm. The species exhibits a notably broad geographic distribution spanning the Americas from Canada to Argentina, with additional populations established in Hawaii and Italy through human introduction.
Bembidion nigropiceum
Bembidion nigropiceum is a small, flightless ground beetle native to Europe, introduced to Massachusetts in the late 1800s via ship ballast. It occupies a highly specialized intertidal habitat in coarse gravel at the high-tide line. The species was rediscovered in 2007–2008 on Boston Harbor Islands after being presumed extinct in North America since 1897. In Great Britain, it is considered Nationally Scarce and protected under the UK Biodiversity Action Plan due to habitat loss.
Bembidion tetracolum
Seine Riverbank Ground Beetle
Bembidion tetracolum is a species of ground beetle in the family Carabidae, first described by Thomas Say in 1823. It is native to Europe and has been introduced to other regions including Australia. The species is commonly known as the Seine Riverbank Ground Beetle, reflecting its association with riparian habitats. It belongs to the large genus Bembidion, which contains numerous small, often metallic ground beetles.
Berytinus minor
common stiltbug
Berytinus minor is a stilt bug (family Berytidae) native to Europe, North Africa, and parts of Asia that has been introduced to North America. The species exhibits wing polymorphism, occurring in both long-winged and short-winged forms with associated morphological differences in the pronotum. It is strongly associated with white clover (Trifolium repens) as a food plant and has been studied in detail at introduced populations in New York State.
Bisnius fimetarius
Bisnius fimetarius is a rove beetle in the family Staphylinidae, originally described from Europe and now known to occur across the Palearctic region. The species has been introduced to eastern Canada. As a member of the genus Bisnius, it belongs to a group of rove beetles often associated with dung and carrion habitats where they function as predators.
Blaniulus guttulatus
Spotted Snake Millipede
Blaniulus guttulatus, the spotted snake millipede, is a small, eyeless millipede native to Central and Western Europe that has been widely introduced to North America, Australia, and remote Atlantic islands. It is characterized by its slender, pale body with distinctive red ozadenes (defensive glands) on each segment. The species thrives in anthropogenic habitats and can become an agricultural pest, particularly during drought conditions.
Blastodacna atra
Apple Pith Moth
Blastodacna atra, commonly known as the apple pith moth, is a small moth in the family Elachistidae. It is native to most of Europe and has been introduced to North America, where it has been recorded in Massachusetts and Ontario. The species is notable for its larval habit of mining inside the young shoots of apple trees (Malus species), which can cause localized damage to orchards. Adults are active from May through September in western Europe.
Blastopsylla
eucalypt shoot psyllid
Blastopsylla is a genus of psyllids in the family Aphalaridae. The genus contains at least one economically significant species, Blastopsylla occidentalis, native to Australia and introduced to multiple continents including the Americas, Africa, Asia, and Europe. Species in this genus are associated with Eucalyptus species, feeding on plant sap and causing damage to shoot tips.
Bledius gallicus
Bledius gallicus is a rove beetle in the family Staphylinidae, first described by Gravenhorst in 1806 under the name Oxytelus gallicum. The species has a broad native distribution across Europe, Russia, the Caucasus, Middle East, Central Asia, Mongolia, and China. It has been introduced to eastern North America, with established populations in Canada and the northeastern United States. The genus Bledius comprises species often associated with sandy or muddy habitats, though specific ecological details for B. gallicus remain limited in published sources.
Borkhausenia
Borkhausenia is a genus of concealer moths in the family Oecophoridae, described by Jacob Hübner in 1825. It belongs to the subfamily Oecophorinae and is probably closely related to Hofmannophila (brown house moth). The genus has a cosmopolitan distribution with species recorded from Europe, Australia, South America, North America, Africa, and Asia. Several other oecophorid genera, including Schiffermuelleria and Metalampra, have historically been included in Borkhausenia. The genus contains approximately 50 described species, though taxonomic boundaries have shifted over time.
Brachymyrmex minutus
Hairy Yellow Rover Ant
A small ant species in the genus Brachymyrmex, native to South America with introduced populations in the United States. The species is commonly known as the Hairy Yellow Rover Ant and has been documented in Brazil and the conterminous 48 United States.
Bradycellus harpalinus
European Harp Ground Beetle
Bradycellus harpalinus is a small ground beetle in the family Carabidae with a trans-Atlantic distribution spanning Europe and North America. The species has been introduced to North America from its native European range. It inhabits open, disturbed habitats and is frequently recorded in agricultural settings.
Broscus cephalotes
coastal ground beetle
Broscus cephalotes is a nocturnal, flightless ground beetle in the family Carabidae. It is native to coastal regions of temperate Europe and western Siberia, and was introduced to eastern Canada around 1975, subsequently spreading into the United States. The species is recognized as beneficial in agricultural contexts due to its predatory habits.