Bark-dwelling
Guides
Agulla
Common Snakeflies
Agulla is a genus of modern snakeflies (Raphidiidae) characterized by an elongated prothorax that creates a distinct "neck" appearance. These predatory insects inhabit wooded areas and are associated with tree bark. The genus belongs to an order considered living fossils, with modern species closely resembling Jurassic-era relatives from 140 million years ago.
Anthribus
fungus weevils
Anthribus is a genus of fungus weevils in the family Anthribidae. Species occur in forest habitats including coniferous, deciduous, and mixed forests. Adults of Anthribus nebulosus have been observed to overwinter in bark crevices of coniferous trees with thicker bark. Flight activity is seasonal and weather-sensitive, with observed activity from May to July in central European populations.
Anthribus nebulosus
fungus weevil
Anthribus nebulosus is a small fungus weevil in the family Anthribidae. Native to Europe, the Near East, and Northern Asia (excluding China), it has been introduced to North America. Adults overwinter in bark cracks of coniferous trees, particularly those with thicker bark such as Scots pine and larch. Flight activity occurs primarily from early May to mid-June, peaking in late May and early June, though timing varies with weather conditions and altitude.
Aradus aequalis
Aradus aequalis is a species of flat bug in the family Aradidae, first described by Thomas Say in 1832. It is one of approximately 200 species in the genus Aradus. Like other flat bugs, it has a strongly dorsoventrally flattened body form adapted for living in tight spaces under bark. The species is known from North America, with records from the United States including Vermont.
Aradus borealis
flat bug
Aradus borealis is a species of flat bug in the family Aradidae, a group of true bugs characterized by their dorsoventrally flattened bodies. The species is found in North America. Flat bugs in this family are typically associated with dead wood and bark habitats. Beyond basic taxonomic placement and geographic distribution, specific biological details for A. borealis remain poorly documented in the available literature.
Aradus concinnus
Aradus concinnus is a species of flat bug in the family Aradidae, described by Bergroth in 1892. Flat bugs in this genus are typically associated with dead wood habitats, living on and under bark where they feed on fungal hyphae. The species is recorded from North America, though specific details about its biology and distribution within this range remain poorly documented in available sources.
Aradus evermanni
Aradus evermanni is a flat bug species described by Van Duzee in 1920. Members of the family Aradidae are characterized by their extremely flattened bodies, an adaptation for living in tight spaces under bark or in decaying wood. The genus Aradus is one of the largest in the family, with species primarily associated with coniferous and deciduous trees. Specific ecological details for A. evermanni remain poorly documented.
Aradus furnissi
Aradus furnissi is a species of flat bug in the family Aradidae, described by Usinger in 1936. Like other members of this family, it is a small, dorsoventrally flattened true bug. The genus Aradus is the largest in the family Aradidae, with species typically associated with dead wood habitats.
Aradus insolitus
flat bug
Aradus insolitus is a species of flat bug in the family Aradidae, described by Van Duzee in 1916. It is distributed in North America, particularly in the western Nearctic region including California. Like other members of the genus Aradus, it belongs to a group of true bugs adapted to living in concealed habitats such as under bark. The species is represented by limited observational records, with 22 observations documented on iNaturalist.
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.
Aradus medioximus
Aradus medioximus is a species of flat bug in the family Aradidae, described by Parshley in 1921. The genus Aradus comprises bark-dwelling true bugs commonly associated with dead wood habitats. Species in this genus are characterized by their dorsoventrally flattened bodies, an adaptation for living under bark. As with other members of Aradidae, they are thought to feed on fungal hyphae and decaying organic matter, though specific details for A. medioximus remain poorly documented. The species is recorded from North America.
Aradus nr-behrensi-calif
California near Aradus behrensi
Aradus nr-behrensi-calif is a flat bug species in the family Aradidae, designated with the "nr" (near) prefix indicating it closely resembles but may not be conspecific with Aradus behrensi. The "calif" suffix suggests California origin. Flat bugs in this genus are typically associated with dead wood habitats. This designation is commonly used in entomological collections when precise species identification requires further taxonomic verification.
Aradus patibulus
Aradus patibulus is a species of flat bug in the family Aradidae, described by Van Duzee in 1927. The genus Aradus comprises bark-dwelling true bugs commonly found on and under the bark of dead trees. Species in this genus are frequently preserved as inclusions in Baltic amber, with 14 species documented from such deposits.
Aradus similis
flat bug
Aradus similis is a species of flat bug in the family Aradidae, described by Thomas Say in 1832. It is native to North America and belongs to a group of insects commonly known as flat bugs due to their strongly dorsoventrally flattened bodies. Members of the genus Aradus are typically associated with dead wood and bark habitats. The species is one of many in a genus with both extant and fossil representatives, including species preserved in Baltic amber dating to the Eocene epoch.
Aradus vandykei
Aradus vandykei is a species of flat bug in the family Aradidae, described by Van Duzee in 1927. It belongs to a genus of true bugs commonly associated with dead wood habitats. The species is part of a diverse group of Hemiptera known for their dorsoventrally flattened bodies and cryptic lifestyle under bark.
Attidops cinctipes
A minute jumping spider in the family Salticidae, measuring 2–3 mm at maturity. The species name refers to its banded legs. It occurs in the United States and Mexico around the Gulf of Mexico, where it inhabits trees and woody surfaces. Its coloration provides camouflage against bark.
Brachyrhynchus
Brachyrhynchus is a genus of true bugs in the family Aradidae (flat bugs). These insects are characterized by their dorsoventrally flattened bodies and are typically found in association with decaying wood and bark habitats. The genus has been documented in 467 iNaturalist observations. Taxonomic placement has been historically confused, with some sources previously associating the name with weevils (Curculionidae), but current consensus places Brachyrhynchus within Hemiptera: Aradidae.
Callopistromyia strigula
Callopistromyia strigula is a small picture-winged fly (family Ulidiidae) found in Canada and the northeastern United States. Adults measure approximately 3.5-5.5 mm and display patterned wings characteristic of the family. Males perform distinctive courtship displays, raising their wings perpendicular to the body while moving sideways on fence rails or logs. The species is closely related to C. annulipes, the "Peacock Fly," and shares its behavioral repertoire.
Centruroides vittatus
Striped Bark Scorpion
Centruroides vittatus is the most common scorpion in the United States, occurring throughout the midsection of the country and northern Mexico. This species exhibits notable behavioral flexibility, including plant climbing and temperature-modulated antipredator responses. Populations show geographic variation in venom toxicity, with eastern populations exhibiting reduced toxicity linked to lower sodium β toxin gene expression. The species has been documented harboring the endosymbiont Mycoplasma vittatus, the first Mycoplasma species identified from an arachnid.
Coriarachne
Coriarachne is a genus of crab spiders (Thomisidae) described by Thorell in 1870. The genus currently contains four species distributed across boreal and temperate regions of Europe, Asia, and North America. Many previously described species have been synonymized or transferred to related genera including Bassaniana, Bassaniodes, and Pycnaxis.
Coriarachne brunneipes
Brown-legged Crab Spider
Coriarachne brunneipes is a species of crab spider in the family Thomisidae, commonly known as the Brown-legged Crab Spider. It occurs across the United States and Canada. The species is known for its habitat association with tree bark and documented maternal care behavior.
Cryphoeca
Cryphoeca is a genus of small araneomorph spiders first described by Tamerlan Thorell in 1870. The genus name derives from Greek meaning "hidden," reflecting its reclusive habits beneath loose bark and within stone walls. The genus contains twelve described species with a Holarctic distribution spanning North America, Europe, and Asia. Cryphoeca species are nocturnal and among the larger members of their subfamily, reaching nearly eight millimeters in body length.
Gonatista grisea
Grizzled Mantis, Florida Bark Mantis, Lichen Mimic Mantis
Gonatista grisea is a bark-dwelling praying mantis native to the southeastern United States. It exhibits exceptional cryptic coloration resembling lichen, earning it the common name "lichen mimic mantis." The species perches head-down on tree trunks to ambush prey and has been documented in Florida, Alabama, and surrounding states. It is one of over twenty native mantis species in the United States, though less frequently encountered than introduced species.
Leptopsaltriini
Painted Cicadas
Leptopsaltriini is a tribe of cicadas comprising at least 200 described species distributed across the Palearctic, Nearctic, and Indomalayan realms. The tribe is organized into six subtribes, with notable diversity in South and Southeast Asia. A recently described genus, Versicolora, has revealed the first documented case of colour-changing behaviour in the superfamily Cicadoidea.
Lobogynioides
Lobogynioides is a genus of mesostigmatic mites in the family Diplogyniidae. The genus is known from Eastern Europe and the Caucasus region. Members are associated with beetles through obligatory phoretic relationships and exhibit kleptoparasitic feeding behavior. The single well-documented species, L. andreinii, develops from egg to adult in 48–60+ days at 18–22°C.
Maculolachnus
Maculolachnus is a genus of aphids in the family Aphididae, established by Gaumont in 1920. Species in this genus are specialized feeders on woody plants in the family Rosaceae, particularly Rosa species. The genus has been documented in Europe, Northern America, and South Korea, with recent integrative taxonomic studies revealing previously unrecognized species diversity in East Asia.
Mezira vanduzeei
Mezira vanduzeei is a species of flat bug in the family Aradidae, described by Usinger in 1936. The species belongs to a family of true bugs known for their extremely flattened bodies, an adaptation for living in narrow spaces under bark and in decaying wood. Like other aradids, this species likely feeds on fungal hyphae in its concealed microhabitats. Records indicate presence in North America, though detailed biological information remains sparse.
Microtomus luctuosus
Tamaulipan White-winged Assassin
Microtomus luctuosus is a species of assassin bug in the family Reduviidae, native to the Americas. It belongs to the subfamily Hammacerinae, which includes species commonly known as bark assassin bugs. The species has been recorded across a broad geographic range spanning North, Central, and South America. Like other members of its genus, it is likely associated with woodland habitats and cryptic microhabitats such as beneath bark. The specific epithet 'luctuosus' (Latin for 'mournful' or 'sorrowful') may refer to its coloration.
Murricia uva
Murricia uva is a species of hersiliid spider described by Foord in 2008. It belongs to the family Hersiliidae, commonly known as tree trunk spiders, recognized for their elongated spinnerets and cryptic bark-dwelling habits. The species is documented from Central Africa, with confirmed records spanning Cameroon to Uganda. Like other hersiliids, it likely exhibits the family's characteristic morphology and behavior, though species-specific details remain limited.
Neanura muscorum
Moss Springtail
Neanura muscorum is a common European springtail species in the family Neanuridae. It is frequently encountered in bark habitats and is characterized by its lack of a furca (springing organ), warty body texture, and blueish-grey coloration. The species feeds on small plants and fungi growing on bark surfaces.
Neotama mexicana
Mexican Two-tailed Spider, Long-spinneret Spider
Neotama mexicana is a species of tree trunk spider in the family Hersiliidae, commonly known as the Mexican two-tailed spider or long-spinneret spider. It is distinguished by its elongated posterior spinnerets, which extend conspicuously beyond the abdomen. The species has been documented from the southern United States through Central America to northern South America, including Peru and Guyana. It is an arboreal species associated with tree trunks and bark habitats.
Neuroctenus
flat bugs
Neuroctenus is a genus of flat bugs in the family Aradidae, subfamily Mezirinae, containing approximately 7 described species. Species in this genus are characterized by their strongly flattened bodies adapted for living under bark and in decaying wood. They are mycophagous, feeding on fungal mycelium, and have been documented in East and Southeast Asia including Taiwan, Hainan, Yunnan, Guizhou, and Tibet. Several species have been studied through mitochondrial genome sequencing, revealing close phylogenetic relationships within the genus and placement of Neuroctenus as sister to Mezira within Mezirinae.
Neuroctenus unistellatus
Neuroctenus unistellatus is a flat bug species in the family Aradidae, described from North America in 1994. Flat bugs in this genus are characterized by their extremely dorsoventrally flattened bodies, an adaptation associated with living under bark or in other tight spaces. The species epithet "unistellatus" suggests a distinctive single spotting or marking pattern. Like other aradids, it likely inhabits forested environments where it feeds on fungal hyphae.
Olisthaerus substriatus
Striped Bark Rove Beetle
Olisthaerus substriatus is a small rove beetle in the subfamily Olisthaerinae, one of the few rove beetle lineages adapted to life under bark. It has a Holarctic distribution spanning northern North America and Eurasia. The species is associated with dead and decaying wood, where it inhabits the space beneath bark on standing or fallen trees. Its common name refers to the longitudinal striations on the elytra.
Pericalina
Pericalina is a subtribe of ground beetles (Carabidae: Lebiinae: Lebiini) comprising arboreal species distributed across tropical and subtropical forests of the New World and Asia. The subtribe includes several complexes distinguished by morphological characters of the mouthparts, pronotum, and ovipositor. New World eucheiloid members are characterized by securiform labial palpomere 3, serrate-setose pronotal margins, and flattened stylomere 2 of the ovipositor. Asian members such as Pericalus exhibit flattened body forms adapted for life under bark. The group has undergone significant diversification in tropical South America with subsequent northward dispersal into Central America and independent radiations in Asia.
Philodromus vulgaris
longlegged crab spider
Philodromus vulgaris is a running crab spider in the family Philodromidae, commonly known as the longlegged crab spider. It is a small to medium-sized spider found across North America, including the United States and Canada. The species belongs to a genus known for its flattened body form and laterigrade leg orientation, adaptations that facilitate sideways movement and hunting on flat surfaces. It is one of numerous Philodromus species documented in the region, though specific biological details remain limited in published literature.
Platycryptus
Tan Jumping Spider
Platycryptus is a genus of jumping spiders (Salticidae) described by D. E. Hill in 1979. The name derives from Greek 'platy' (flat) and 'crypt' (hidden), referring to their flattened bodies and habit of hiding in crevices. These spiders are characterized by cryptic gray and brown coloration with hairy bodies. They are active hunters found on tree bark and wooden structures, with four recognized species distributed across North America, Central America, and Brazil.
Platysoma coarctatum
clown beetle
Platysoma coarctatum is a species of clown beetle in the family Histeridae. It is found throughout North America, with records across Canada and the United States. Like other members of the genus, it inhabits spaces under bark and is a predator of other insects.
Polyxenida
bristle millipedes, bristly millipedes, pincushion millipedes
Polyxenida is an order of millipedes distinguished by a soft, non-calcified exoskeleton covered in distinctive tufts of bristles. They are the only living members of the subclass Penicillata, which represents the most basal lineage of living millipedes. This order comprises approximately 148 species across four families worldwide. Polyxenida exhibit several unique derived traits including indirect sperm transfer via spermatophores deposited in webs, and a mechanical defense using detachable barbed bristles rather than chemical defenses.
Pseudeuophrys erratica
Black-palped Jumping Spider
Pseudeuophrys erratica is a small jumping spider native to Europe and Asia that has been introduced to the eastern and western United States. Unlike its congener P. lanigera, which is abundant in and around buildings, P. erratica is uncommon and prefers natural habitats. Adults are active primarily in spring and summer, with females persisting into autumn.
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.
Scolopocryptops spinicaudus
Thorn-tailed Bark Centipede
Scolopocryptops spinicaudus is a centipede species first described by Wood in 1862. It belongs to the family Scolopocryptopidae within the order Scolopendromorpha. The species is known by the common name Thorn-tailed Bark Centipede and has been recorded across North America and parts of southern Asia including Japan. It is one of the more frequently observed centipedes in its range, with over 1,500 citizen science observations documented.
Scoloposcelis
minute pirate bugs
Scoloposcelis is a genus of minute pirate bugs in the family Anthocoridae, established by Fieber in 1864. The genus contains approximately seven described species distributed across Europe and Asia, with records from Scandinavia, Korea, and Malaysia. Species are typically found in concealed microhabitats such as under bark of decaying wood. One species, S. seidaii, was described from a single specimen collected in West Malaysia, representing the first record of the genus from that region.
Stenichneumon culpator
Stenichneumon culpator is a species of ichneumon wasp in the family Ichneumonidae. The species is known to hibernate solitarily in tunnels beneath bark, specifically those created by beetles. It has been recorded across parts of Europe including Austria and Belgium.
Tmarus
Octopus Spiders
Tmarus is a large genus of crab spiders (family Thomisidae) established by Eugène Simon in 1875, with more than 230 described species distributed across all continents except Antarctica. These small to moderate-sized spiders (3.7–7.3 mm body length) are characterized by cryptic bark-like coloration and ambush predatory behavior. The genus exhibits sexual dimorphism, with females typically larger than males.
Ufeus plicatus
Folded Satyr
A small noctuid moth endemic to northeastern North America, closely tied to large poplars—especially eastern cottonwood—growing in riparian habitats with loose, rotting bark. Adults exhibit an unusual bimodal activity pattern with spring emergence followed by summer aestivation and renewed fall activity. The species is notably scarce at light traps despite occurring in suitable habitats.
Vertagopus arboreus
Vertagopus arboreus is a species of elongate-bodied springtail in the family Isotomidae. It is widely distributed across northern Eurasia and parts of Asia. The species is associated with arboreal and ground-level habitats in forested environments. Taxonomic status varies between sources, with some authorities treating it as a synonym of Vertagopus asiaticus.