Woodlouse
Guides
Alloniscus mirabilis
Wonderful Wracklouse
Alloniscus mirabilis is a terrestrial isopod (woodlouse) in the family Alloniscidae. The species epithet "mirabilis" (Latin for "wonderful" or "extraordinary") reflects its distinctive characteristics. As a member of the suborder Oniscidea, it is a fully terrestrial crustacean adapted to life on land. The species has been documented in North America with 81 observations recorded on iNaturalist.
Alloniscus perconvexus
Commando Isopod
Alloniscus perconvexus is a terrestrial isopod in the family Alloniscidae, commonly known as the Commando Isopod. It is a North American endemic with documented observations across the continent. The species belongs to a family of relatively large, robust woodlice that exhibit specialized adaptations for arid and semi-arid environments.
Androniscus
Androniscus is a genus of small woodlice in the family Trichoniscidae, established by Verhoeff in 1908. The genus includes the well-known species Androniscus dentiger, commonly called the rosy or pink woodlouse. Members of this genus are characterized by their small size, distinctive coloration, and association with calcareous environments. Some populations show cave-adapted ecology, particularly in the southern part of their range.
Armadillidium
pill woodlice, leg pebbles, pill bugs, roly-poly, potato bugs
Armadillidium is a genus of terrestrial crustaceans commonly known as pill bugs or roly-polies, distinguished by their ability to roll into a ball when disturbed (conglobation). The genus contains approximately 189 recognized species, most endemic to Mediterranean regions. These detritivores inhabit moist environments and play important roles in decomposition. The most widespread species, A. vulgare, has been introduced globally and serves as a soil bioindicator.
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.
Armadillidium vulgare
common pill-bug, common pill woodlouse, roly-poly, potato bug, doodle bug, carpenter
Armadillidium vulgare is a terrestrial isopod native to Mediterranean Europe that has become one of the most widespread woodlouse species globally through human-mediated dispersal. It is the most extensively studied terrestrial isopod and serves as a model organism for research on mitochondrial genome evolution, desiccation resistance, and conglobation behavior. The species exhibits remarkable morphological plasticity, including numerous color morphs maintained through selective breeding in the pet trade.
Armadilloniscus
Driftclingers
Armadilloniscus is a genus of terrestrial isopods (woodlice) in the family Detonidae, first described by Uljanin in 1875. The genus contains at least 30 described species, commonly referred to as driftclingers. These organisms are part of the diverse crustacean fauna found in various terrestrial and coastal environments.
Atlantoscia floridana
Florida Fast Woodlouse
Atlantoscia floridana is a terrestrial isopod (woodlouse) in the family Philosciidae. The species has been documented in North America, South America, and Africa, indicating a broad transatlantic distribution. It is known to be relatively fragile compared to other woodlice but naturally high in calcium content. In captive settings, it shows preferences for specific humidity gradients.
Brackenridgia
woodlice
Brackenridgia is a genus of small terrestrial isopods (woodlice) in the family Trichoniscidae, established by Ulrich in 1902. The genus contains nine described species distributed primarily in North America, with several species exhibiting troglomorphic adaptations for cave-dwelling. Species in this genus are typically found in moist, dark microhabitats including caves, forest litter, and rocky crevices.
Chaetophiloscia
Chaetophiloscia is a genus of small terrestrial isopods in the family Philosciidae, established by Verhoeff in 1908. The genus is native to the northern Mediterranean region, with at least two species documented: C. sicula, which has become invasive in North America and parts of Europe, and C. elongata, studied in North African coastal habitats. Species in this genus are characterized by their association with moist, anthropogenic, and coastal environments, and their capacity for rapid range expansion through human-mediated transport.
Cixius yufengi
Cixius yufengi is a species of planthopper in the family Cixiidae, described by Tsaur in 1993. The species belongs to a genus of small, often inconspicuous insects that feed on plant sap. Very little specific information is available about this particular species.
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Reclined Pill Woodlice
Cubaris is a genus of woodlice (terrestrial isopods) in the family Armadillidae, established in 1833 with Cubaris murina as the type species. The genus contains more than 100 described species, though it has become a wastebasket taxon with many species placed in it that do not fit the original description. Species in this genus are capable of conglobation (rolling into a ball) and have been widely used in ecotoxicity testing due to their sensitive behavioral responses to soil contaminants. Several Cubaris species, particularly undescribed forms such as "Rubber Ducky," have become popular in the pet trade.
Cubaris murina
little sea isopod, little sea roly poly, little sea pillbug, little sea pill woodlouse
Cubaris murina is a small terrestrial isopod (woodlouse) in the family Armadillidae, notable for its ability to conglobate—roll into a complete ball when disturbed. The species reaches approximately 11 mm in length and 5 mm in width. It has a remarkably broad geographic distribution spanning tropical and subtropical regions across multiple continents, with populations in the Caribbean, South America, Southeast Asia, and the Pacific. The species has become popular in the exotic pet trade due to its bioactive utility in terrariums and the development of several color morphs through selective breeding.
Cylisticus
Cylisticus is a genus of woodlice (terrestrial isopods) in the family Cylisticidae, containing at least 70 described species. These soil-dwelling crustaceans are found in tropical and temperate regions, where they inhabit the upper soil layers. At least one species, C. convexus, has been studied as a tropical soil decomposer with limited vertical dispersal ability. The genus is part of the diverse oniscidean fauna contributing to litter breakdown and nutrient cycling.
Cylisticus convexus
Curly Woodlouse
Cylisticus convexus, commonly known as the curly woodlouse, is a small terrestrial isopod first described by Charles De Geer in 1778. Native to Europe and Asia, it has been introduced to North Africa, North America, and South America. The species is notable for its ability to conglobate (roll into a ball) while retaining protruding antennae and uropods, and for possessing five pairs of pleopodal lungs—features that distinguish it from similar pillbugs.
Detonella papillicornis
woodlouse
Detonella papillicornis is a species of terrestrial isopod (woodlouse) in the family Detonidae. The species was first described by Richardson in 1904. It is one of relatively few documented species in the genus Detonella, a group of woodlice characterized by specific morphological features within the family Detonidae.
Floridoscia
Floridoscia is a genus of terrestrial isopods (woodlice) in the family Philosciidae, described in 1984 by Schultz and Johnson. As members of the suborder Oniscidea, these crustaceans are fully adapted to land. The genus is endemic to Florida and contains species restricted to this region.
Floridoscia fusca
Florida Rufous Woodlouse
Floridoscia fusca is a terrestrial isopod species in the family Philosciidae, commonly known as the Florida Rufous Woodlouse. It is native to North America and belongs to the suborder Oniscidea, which encompasses the majority of terrestrial isopods. The species was described by Schultz and Johnson in 1984.
Hyloniscus riparius
Riparian Woodlouse
A small woodlouse native to Central and Eastern Europe that has established invasive populations in North America since 1951 and is expanding eastward across Russia. It thrives in floodplain environments and can survive prolonged submersion. In invaded regions, it reaches high densities and may dominate local woodlice communities, potentially displacing native species.
Isopoda
isopods, woodlice, pillbugs, sowbugs, sea slaters, gribbles
Isopoda is an ancient order of crustaceans encompassing over 10,000 described species across marine, freshwater, and terrestrial habitats. Members are characterized by dorsoventrally flattened bodies, seven pairs of similar walking legs (giving the group its name from Greek iso- "equal" and pod- "foot"), and two pairs of antennae. The order exhibits exceptional morphological diversity, ranging from minute interstitial forms to giant deep-sea species exceeding 30 cm in length. Isopods lack a carapace, instead possessing overlapping dorsal plates that provide flexibility and protection. Females brood eggs in a specialized marsupium formed by oostegites under the thorax.
Ligia occidentalis
Western Sea Slater
Ligia occidentalis is a supralittoral isopod inhabiting rocky shorelines along the eastern Pacific coast. The species occupies the high intertidal zone, hiding in crevices above the high tide line during daytime to avoid desiccation and emerging nocturnally to feed. It is distinguished from the sympatric Ligia pallasii by longer uropods, larger eyes set closer together, and a sleeker body form. The species harbors mycoplasma-like bacteria as hepatopancreas symbionts and shows remarkable morphological stasis across highly genetically divergent allopatric lineages.
Ligia oceanica
sea slater, common sea slater, sea roach
Ligia oceanica is a large intertidal isopod reaching up to 35 mm in length, making it the largest species in the suborder Oniscidea. Native to rocky Atlantic coasts of Europe, it has been introduced to eastern North America and Atlantic islands. This semelparous species inhabits the supralittoral zone, hiding in rock crevices by day and emerging nocturnally to feed. Molecular phylogenetics suggests closer affinity to marine isopod suborders Valvifera and Sphaeromatidea than to terrestrial woodlice, challenging traditional classification.
Ligidium elrodii
Eastern Rockslater, rock slater
Ligidium elrodii is a terrestrial isopod species in the family Ligiidae, commonly known as the Eastern Rockslater. It is native to North America, with documented presence in both the United States and Canada. The species includes five recognized subspecies, described by Schultz in 1970 from various geographic locations. It belongs to a family of rock-dwelling woodlice adapted to moist, rocky microhabitats.
Ligidium kofoidi
Kofoid's Rockslater
Ligidium kofoidi is a species of woodlouse in the family Ligiidae, described by Maloney in 1930. It is a small to medium-sized terrestrial isopod found in North America. The species is rarely documented, with only a handful of observations recorded. As a member of the genus Ligidium, it inhabits moist terrestrial environments and belongs to a group commonly known as rockslaters.
Littorophiloscia richardsonae
Western Saltmarsh Woodlouse
Littorophiloscia richardsonae is a small terrestrial isopod commonly known as the Western Saltmarsh Woodlouse. It belongs to the family Halophilosciidae and has been documented primarily in coastal saltmarsh habitats of western North America. The species was described in 1909 and represents one of the few truly halophilic (salt-tolerant) woodlice in the region.
Littorophiloscia vittata
Eastern Saltmarsh Woodlouse
Littorophiloscia vittata is a woodlouse species in the family Halophilosciidae, native to the east coast of North America. It inhabits saltmarsh environments, typically found under boards and debris. The species was first described by Thomas Say in 1818. As a member of the suborder Oniscidea, it belongs to the diverse group of terrestrial isopods commonly known as woodlice or pill bugs.
Melanophora
woodlouse flies
Melanophora is a genus of small parasitoid flies commonly known as woodlouse flies. Species are internal parasitoids of terrestrial isopods (woodlice), with larvae developing inside and eventually killing their hosts. The genus has a broad distribution across multiple biogeographic regions, including native Palaearctic and Afrotropical ranges and introduced populations in the Nearctic and Neotropics. Adults are typically active from spring through autumn and are often observed resting on light-coloured vertical surfaces.
Miktoniscus spinosus
Eastern Mikto
Miktoniscus spinosus is a small terrestrial isopod in the family Trichoniscidae, commonly known as the Eastern Mikto. It belongs to the suborder Oniscidea, which encompasses the familiar woodlice and pill bugs. The species is native to the eastern United States, with documented presence in New England. As a member of the Synocheta, it represents one of the more derived lineages of terrestrial isopods.
Nagurus
Nagurus is a genus of terrestrial isopods in the family Trachelipodidae, established by Holthuis in 1949. These woodlice are found in tropical and subtropical regions, with records from northern Europe and Southeast Asia suggesting either introduced populations or broader native distribution than currently documented. The genus comprises small to medium-sized isopods adapted to life on land.
Niambia capensis
African Cape Isopod
Niambia capensis is a species of woodlouse in the family Platyarthridae, first described by Dollfus in 1895. It is native to Africa, with records from South Africa and Namibia, and has been introduced to North America. This terrestrial isopod belongs to the suborder Oniscidea, which contains the familiar pillbugs and sowbugs. The species represents one of the few documented cases of transoceanic dispersal in terrestrial isopods, likely through human-mediated transport.
Oniscidea
Woodlice, Pillbugs, Rock Slaters
Oniscidea is the suborder of terrestrial isopod crustaceans commonly known as woodlice, pillbugs, and rock slaters. This diverse group comprises over 5,000 described species that have successfully colonized land from ancestral marine isopod stock. They are characterized by a dorsoventrally flattened, segmented exoskeleton with seven pairs of walking legs, and occupy a wide range of habitats from forests and grasslands to caves and urban environments. Most species are nocturnal detritivores that play important roles in decomposition and nutrient cycling.
Oniscus
woodlice
Oniscus is a genus of terrestrial isopods (woodlice) in the family Oniscidae. The genus comprises five species with restricted distributions: three species are endemic to northwestern Iberia (O. ancarensis, O. galicianus, O. lusitanicus), one to the Pyrenees (O. simonii), and one species, O. asellus, is widespread across Europe and has been introduced to the Americas. O. asellus has been studied for its ability to fragment weathered polystyrene plastic into microplastics in laboratory settings.
Philoscia muscorum
Common Striped Woodlouse, Fast Woodlouse
Philoscia muscorum is a common European woodlouse notable for its rapid movement and distinctive appearance. It exhibits a unique life history strategy called year class splitting, where individuals from the same reproductive cohort diverge into two developmental pathways: faster-growing individuals mature and reproduce in their first year, while slower-growing individuals delay maturation until their second year. This species has successfully established introduced populations in eastern North America, including New England, the mid-Atlantic states, and the Pacific Northwest.
Platyarthrus
Platyarthrus is a genus of small, blind woodlice comprising over 30 described species. Members are obligate myrmecophiles, living almost exclusively within ant nests. The genus exhibits female-biased sex ratios in small populations. Body size in at least some species is dependent on host ant species.
Porcellio scaber
Common Rough Woodlouse, Rough Woodlouse
Porcellio scaber is a European woodlouse species with a cosmopolitan distribution, now found across North America, South Africa, Australia, and sub-Antarctic islands through human-mediated dispersal. It is one of the most abundant and widespread terrestrial isopods in many regions, including the United Kingdom where it is considered one of the 'big five' woodlouse species. The species is notable for its rough, tuberculate exoskeleton and inability to conglobate (roll into a ball), instead relying on tonic immobility and chemical defenses when threatened. Research has documented individual personality traits in this species, expressed through consistent differences in defensive behavior duration.
Porcellio spinicornis
Brickwork Woodlouse
Porcellio spinicornis is a medium-sized terrestrial isopod in the family Porcellionidae, native to Europe and introduced to North America. It is distinguished by prominent spiny frontal lateral lobes, the feature referenced in its species name. The species is nocturnal and detritivorous, feeding on dead plant material. It exhibits direct development with eggs and juveniles carried in a fluid-filled marsupium until the first juvenile stage.
Porcellionides
woodlice
Porcellionides is a genus of terrestrial isopods (woodlice) in the family Porcellionidae, characterized by cosmopolitan distribution and ecological adaptability. Species within this genus exhibit notable intraspecific variation in reproductive strategies, with some populations showing seasonal reproduction and others continuous breeding activity. The genus has been extensively studied for its population dynamics, behavioral ecology, and sensitivity to environmental stressors, making it a valuable model organism for soil health assessment.
Porcellionides floria
Flowery Blue Isopod
Porcellionides floria is a species of terrestrial isopod (woodlouse) in the family Porcellionidae, first described by Garthwaite and Sassaman in 1985. The species has been recorded in North America and Mexico, with 89 observations documented on iNaturalist as of the source date. Like other members of its family, it is a detritivorous crustacean adapted to life on land.
Porcellionides pruinosus
Powderblues, powder blue woodlouse
Porcellionides pruinosus is a cosmopolitan terrestrial isopod (woodlouse) native to Europe that has achieved global distribution through human-mediated dispersal. The species is detritivorous and occupies diverse terrestrial habitats from agricultural fields to desert margins. It is suspected to represent a cryptic species complex, with ten subspecies currently recognized and significant morphological and reproductive variation documented across populations. The species carries Wolbachia endosymbionts that can induce feminization of males and cytoplasmic incompatibility, affecting population sex ratios. P. pruinosus has become popular in the pet trade, with numerous color morphs selectively bred.
Porcellionides virgatus
Oak Woodlouse
Porcellionides virgatus is a terrestrial isopod commonly known as the Oak Woodlouse. It is a member of the family Porcellionidae and has been documented across North America including the United States and Mexico. The species is frequently recorded in citizen science observations.
Proporcellio vulcanius
Proporcellio vulcanius is a terrestrial isopod in the family Porcellionidae, described by Verhoeff in 1908. The species belongs to a genus characterized by reduced pleopodal lungs and adaptation to drier microhabitats compared to many woodlice. Records indicate presence across parts of Europe and northern Asia. The specific epithet 'vulcanius' suggests possible association with volcanic or warm habitats, though this has not been formally verified.
Rhinophoridae
Woodlouse Flies
Rhinophoridae is a small family of calyptrate flies (Diptera) comprising 33 genera and approximately 177 species. The family is distinguished by a highly specialized life history: larvae are obligate parasitoids of terrestrial isopods (woodlice), a feeding strategy unique among all insects. Adults lack morphological autapomorphies and are difficult to identify without examination of male terminalia or first-instar larvae. The group was historically considered primarily Palaearctic in distribution, but recent sampling has revealed substantial diversity in tropical and southern hemisphere regions.
Rhyscotus
armadillo woodlice
Rhyscotus is a genus of armadillo woodlice in the family Rhyscotidae, first described by Gustav Budde-Lund in 1885. The genus contains twelve recognized species distributed across multiple continents. Members of this genus are terrestrial isopods adapted to life on land.
Rhyscotus texensis
Texas Woodlouse
Rhyscotus texensis is a terrestrial isopod endemic to Texas, commonly known as the Texas Woodlouse. It belongs to the family Rhyscotidae, a small group of woodlice restricted to the Americas. The species was first described by Richardson in 1905. It is one of the few endemic woodlice species with a well-documented restricted range in North America.
Trachelipus rathkii
Rathke's Woodlouse
Trachelipus rathkii is a medium-sized European woodlouse introduced to North America, where it has established populations across the northern United States and southern Canada. It is distinguished by its tolerance for flooding and poorly drained habitats, often dominating riverside and floodplain communities. The species serves as a documented host for the nematode Caenorhabditis remanei, which associates with it as dauer larvae on its dorsal plates and ventral appendages.
Trichoniscidae
Trichoniscidae is a family of terrestrial isopods (woodlice) notable for containing the most abundant British woodlouse, *Trichoniscus pusillus*. The family exhibits exceptional ecological diversity, with many species occupying subterranean habitats in karst regions across Europe, while others have secondarily adapted to aquatic or amphibious lifestyles. Multiple genera contain troglobiotic (obligate cave-dwelling) species, particularly in the Dinaric Karst, which harbors significant diversity of this family. Some species demonstrate unique morphological adaptations for cave life, including elongated appendages and modified mouthparts.
Trichoniscus pygmaeus
Least Pygmy Woodlouse
Trichoniscus pygmaeus is a minute terrestrial isopod commonly known as the Least Pygmy Woodlouse. It is native to Britain and Ireland, with a limited introduced distribution in the United States. The species is among the smallest woodlice in its native range, measuring approximately 2.5 mm in length. Its translucent, pinkish-yellow coloration and diminutive size distinguish it from other European woodlice.
Tylos punctatus
Spotted Calloused Beach Pillbug
Tylos punctatus is a large, strictly nocturnal sand-beach isopod inhabiting sheltered intertidal zones from southern California to Baja California. It exhibits remarkable behavioral adaptations to this harsh environment, including precise burrowing cycles synchronized with tidal patterns and seasonal dormancy. The species has an exceptionally slow life history for an isopod, with females breeding only once annually after reaching maturity at approximately three years of age.
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.
Venezillo parvus
Little Pill Woodlouse
Venezillo parvus is a small terrestrial isopod commonly known as the Little Pill Woodlouse. It belongs to the family Armadillidae, a group characterized by their ability to conglobate (roll into a complete ball). The species has been documented in both North America and Europe, with its native range presumed to be European and North American populations representing introduced populations. It is a detritivore that contributes to decomposition processes in terrestrial ecosystems.