Hymenoptera
Guides
Odontomachus desertorum
Desert Trap-jaw Ant
Odontomachus desertorum is a species of trap-jaw ant in the subfamily Ponerinae, first described by Wheeler in 1915. Like other members of the genus, it possesses powerful, spring-loaded mandibles capable of rapid closure to capture prey or propel the ant through the air. The specific epithet 'desertorum' suggests an association with arid environments. As with most Odontomachus species, detailed natural history information for this taxon remains limited in published literature.
Odontophotopsis arcuata
Odontophotopsis arcuata is a species of velvet ant in the family Mutillidae, described by Mickel in 1983. Velvet ants (Mutillidae) are a family of solitary wasps in which females are wingless and often possess aposematic coloration and a powerful sting. The genus Odontophotopsis is characterized by distinctive mandibular and dental structures. This species is part of a diverse group of North American mutillids, though specific biological details for O. arcuata remain poorly documented in published literature.
Odontophotopsis melicausa
A species of velvet ant in the genus Odontophotopsis, first described by Blake in 1871. The genus is characterized by distinctive dental modifications on the mandibles. Like other mutillids, this species exhibits sexual dimorphism with wingless females and winged males.
Odontophotopsis setifera
Odontophotopsis setifera is a species of velvet ant in the family Mutillidae, described by Schuster in 1952. Velvet ants are solitary wasps in which females are wingless and often possess aposematic coloration. The genus Odontophotopsis is part of the diverse Mutillidae fauna of North America.
Oenonogastra
Oenonogastra is a genus of parasitoid wasps in the family Braconidae, first described by Ashmead in 1900. As a member of the Braconidae, it belongs to a large family of wasps that parasitize other insects. The genus is rarely encountered in collections and field observations, with limited published information on its biology.
Oligosita
Oligosita is a genus of minute egg parasitoid wasps in the family Trichogrammatidae, established by Walker in 1851. Members of this genus are cosmopolitan in distribution and have been documented attacking eggs of diverse host groups including Coleoptera, Hemiptera, Lepidoptera, and Thysanoptera. Specific species have been recorded as parasitoids of leafhopper eggs (Cicadellidae) in agricultural and natural systems across Italy, China, and North America. The genus is characterized by its small body size typical of trichogrammatids and distinctive morphological features used in species-level identification.
Oligositini
Oligositini is a tribe of minute parasitoid wasps within the family Trichogrammatidae, established by Viggiani in 1971. Members of this tribe are classified in the subfamily Oligositinae. These chalcid wasps are among the smallest known insects, with most species measuring less than 1 mm in length. The tribe is distinguished by specific wing venation patterns and antennal structures that separate it from related trichogrammatid tribes.
Omalus aeneus
Cuckoo Wasp
Omalus aeneus is a small, metallic cuckoo wasp in the family Chrysididae. Females reach 4.5–5.4 mm in body length, males 4.4–5 mm. The species exhibits striking metallic coloration ranging from blue, green, and purple to nearly black or golden, with greenish-blue abdomen and legs. This cleptoparasitic wasp has two or more generations annually in southern Europe and exploits a remarkable indirect parasitism strategy: females oviposit into living aphids, which are subsequently captured by aphid-hunting crabronid wasps and transported to their nests, where the cuckoo wasp larva develops.
Omalus iridescens
Omalus iridescens is a species of cuckoo wasp in the family Chrysididae. Like other members of the genus Omalus, it is a cleptoparasite that exploits the nesting behavior of solitary wasps. The species exhibits the characteristic metallic coloration typical of chrysidid wasps. Based on documented behaviors of closely related Omalus species, females likely oviposit into aphids that are subsequently captured by crabronid wasps and transported to their nests, where the cuckoo wasp larva develops at the expense of the host's offspring.
Onycholyda quebecensis
Onycholyda quebecensis is a species of sawfly in the family Pamphiliidae, order Hymenoptera. As a member of this family, it is a non-stinging relative of wasps and bees with larvae that develop on plants. The species epithet 'quebecensis' indicates a geographic connection to Quebec, Canada. Very few observations of this species exist in public databases.
Oobius agrili
Oob
Oobius agrili is a tiny, solitary egg parasitoid wasp in the family Encyrtidae, native to Northeast Asia. It is the only egg parasitoid released for biological control of the invasive emerald ash borer (Agrilus planipennis) in North America, where it has been introduced in over 31 US states. The species is parthenogenic, produces multiple generations annually, and achieves partial phenological synchrony with its host's egg-laying period. Individual females can parasitize more than 60 host eggs, with field parasitism rates reaching 60% in optimal conditions.
Ophionellus texanus
Ophionellus texanus is a species of ichneumon wasp in the family Ichneumonidae, first described by Cresson in 1872. It belongs to a genus of parasitoid wasps whose biology remains poorly documented. The species epithet "texanus" indicates a type locality or association with Texas. Like other ichneumonids, it is presumed to be a parasitoid of other insects, though specific host relationships have not been established for this species.
Orasema costaricensis
Orasema costaricensis is a species of parasitic wasp in the family Eucharitidae, first described by Wheeler & Wheeler in 1937. Like other members of the genus Orasema, it is likely a parasitoid of ant larvae, though specific host associations for this species remain poorly documented. The species name indicates its Costa Rican origin. Records from the Galápagos Islands suggest some dispersal capacity or potential human-mediated introduction.
Orasema occidentalis
Orasema occidentalis is a species of chalcid wasp in the family Eucharitidae, first described by William Harris Ashmead in 1892. The species is a known parasite of Pheidole desertorum, a species of ant. Like other members of its family, it likely exhibits the specialized life history typical of Eucharitidae, in which larvae develop as parasitoids within ant colonies.
Oresbius
Oresbius is a genus of parasitoid wasps in the family Ichneumonidae, first described by Marshall in 1867. Species are distributed across Europe and North America. The genus is poorly studied, with limited published information on species biology and ecology.
Orgichneumon calcatorius
Orgichneumon calcatorius is a species of parasitoid wasp in the family Ichneumonidae, first described by Thunberg in 1822. The species belongs to a genus of medium to large-sized ichneumonids characterized by robust body construction and distinctive leg morphology. As with other members of Ichneumonidae, it is presumed to be a parasitoid of other insects, though specific host records for this species remain poorly documented.
Ormocerinae
Ormocerinae is a subfamily of chalcidoid wasps within the family Pteromalidae, established by Walker in 1833. The group contains approximately 40 described genera, including the type genus Ormocerus and the well-known genus Trichilogaster. Members are small parasitoid wasps, though specific biological details remain poorly documented for most taxa.
Ormyrus rosae
Ormyrus rosae is a species of parasitoid wasp in the family Ormyridae, first described by Ashmead in 1885. The species is known from gall-associated habitats in North America, with records from Colorado, Florida, Kansas, New Jersey, and Ontario. As a member of the genus Ormyrus, it likely parasitizes gall-forming insects, though specific host associations for this species remain poorly documented. The species epithet 'rosae' suggests a historical association with rose-feeding hosts, possibly the gall wasp Diplolepis rosae.
Ormyrus venustus
Ormyrus venustus is a species of parasitoid wasp in the family Ormyridae, described by Hanson in 1992. Like other members of the genus Ormyrus, it is a parasitoid of gall-forming insects. The genus Ormyrus has been the subject of recent research revealing extensive cryptic species diversity, with morphologically identical populations often representing multiple genetically distinct species. O. venustus is known from scattered records across the United States including Arizona, California, Colorado, Maryland, and Massachusetts.
Orthogonalys
Orthogonalys is a genus of trigonalid wasps comprising hyperparasitoid species. At least one species, Orthogonalys pulchella, employs a distinctive 'scattershot' approach to host location, a notable behavioral adaptation among parasitoid wasps. The genus belongs to the family Trigonalidae, a group known for complex life histories involving secondary parasitism.
Orthogonalys pulchella
Orthogonalys pulchella is a species of hyperparasitoid wasp in the family Trigonalidae. This species is part of a unique guild of parasitoids that target the larvae of other parasitoid wasps rather than primary hosts. The species was described by Cresson and has been documented in parts of North America.
Orus armiger
Orus armiger is a species of parasitic woodwasp in the family Orussidae, a group notable for their unique evolutionary position and specialized host-finding behavior. The family Orussidae contains only about 75 species worldwide, making it one of the smallest and least understood families of Hymenoptera. Orussid wasps are the only parasitoid wasps that attack wood-boring beetle larvae, using vibrational sounding to locate hosts within solid wood. Adults are rarely encountered in the field and are frequently mistaken for ants due to their appearance and behavior.
Orussus minutus
Orussus minutus is a rarely collected parasitic woodwasp in the family Orussidae, native to the eastern United States. The species is notable for its significant western range expansion documented through citizen science platforms and museum collections. Previously known from only about 50 specimens mainly in the Northeast, new records from Arkansas, Iowa, Minnesota, and Manitoba extend its range hundreds of miles westward. The species is extremely uncommon in collections despite intensive trapping efforts.
Orussus terminalis
Orussus terminalis is a parasitic woodwasp in the family Orussidae, a group unique among woodwasps for their parasitoid lifestyle. Like other orussids, they are rarely encountered in collections and poorly studied. The species belongs to a family whose members attack immature stages of wood-boring beetles and other woodwasps. Orussus terminalis has been recorded from eastern North America, with distribution records from Canada (Ontario, Quebec) and the United States (Vermont).
Orussus thoracicus
Orussus thoracicus is a parasitic woodwasp in the family Orussidae, one of the rarest and most unusual groups of Hymenoptera. Adults are often mistaken for carpenter ants due to their dark coloration and wing-folding behavior. The species has been recorded from Canada, specifically British Columbia, though its biology and ecology remain poorly documented. Like other orussids, it likely parasitizes wood-boring beetle larvae using specialized vibrational sounding to locate hosts.
Osmia gaudiosa
Osmia palmula
Oxaeinae
Oxaeinae is a subfamily of large, fast-flying bees within the family Andrenidae. They are endemic to the Americas, with 19 described species across four genera ranging from the United States to Argentina. Formerly treated as a distinct family (Oxaeidae), they were reclassified as a subfamily in 1995.
Oxybelus cressonii
square-headed wasp
Oxybelus cressonii is a species of square-headed wasp in the family Crabronidae, described by C. Robertson in 1889. It belongs to a genus of predatory wasps that specialize in hunting flies. The species occurs in North America, with records from Canada and the United States. Like other Oxybelus species, it is a solitary wasp that provisions its nest with paralyzed prey.
Pachysomoides fulvus
Pachysomoides fulvus is a small ichneumon wasp that parasitizes paper wasps (Polistes spp.) in North America. The female wasp lays eggs on larvae or pupae inside the exposed paper comb nests of its hosts. It ranges from New York to Florida and west to California and British Columbia, though it does not appear to be abundant anywhere. The species is notable for targeting social wasps that are typically well-defended, making it a specialized parasitoid despite its relatively small size.
Pachysomoides stupidus
Pachysomoides stupidus is a gregarious ichneumon wasp that parasitizes paper wasps (Polistes spp.). Females lay multiple eggs on pre-pupal Polistes grubs, and larvae feed gregariously as external parasites on the pupa. The species exhibits larval competition among siblings for host resources, with males showing more altruistic behavior than females in resource allocation. Brood sex ratios are biased toward females, with investment ratios equalized by egg-layers.
Palaeogryon
Palaeogryon is a genus of parasitoid wasps in the family Scelionidae, first described by Masner in 1969. The genus belongs to the subfamily Scelioninae, a group of minute wasps that parasitize eggs of insects and other arthropods. As with many scelionid genera, Palaeogryon is characterized by morphological adaptations for locating and penetrating host eggs. The genus is part of the diverse platygastroid lineage within Hymenoptera.
Palaeoneura
Palaeoneura is a genus of fairyflies (family Mymaridae) comprising eight described species. These minute parasitoid wasps are found in Northern America and Australia. The genus was established by Waterhouse in 1915, with Palaeoneura evanescens as the type species. Species have been described from 1915 to 2021, with recent taxonomic revisions by Triapitsyn.
Palmodes dimidiatus
Palmodes dimidiatus is a species of thread-waisted wasp in the family Sphecidae. It is a solitary, ground-nesting wasp that hunts katydids (Tettigoniidae) as prey for its larval offspring. The species is known to be parasitized by the kleptoparasitic wasp Stizoides renicinctus, which raids its food caches. Palmodes dimidiatus occurs in North America and Middle America.
Pamphilius
leaf-rolling sawflies
Pamphilius is a genus of approximately 115 species of leaf-rolling sawflies in the family Pamphiliidae. Adults are typically 10–15 mm in length with black bodies, yellowish spots on the head, yellow legs, and transparent wings. Larvae are solitary or colonial leaf-rollers that feed on various deciduous trees and shrubs. The genus has a Holarctic distribution, occurring in North America and Eurasia.
Pamphilius middlekauffi
Pamphilius middlekauffi is a species of sawfly in the family Pamphiliidae, suborder Symphyta. It is one of 30 sawfly species newly recorded in Arkansas during field work by Dr. Michael Skvarla, representing a significant range extension from previously known localities. The species belongs to a group of plant-feeding wasps whose larvae develop on plant material.
Pamphilius semicinctus
Pamphilius semicinctus is a species of web-spinning sawfly in the family Pamphiliidae, suborder Symphyta. As with other members of this genus, the larvae construct silk webs on host plants for protection while feeding. The species belongs to a group of plant-feeding wasps that are economically insignificant and harmless to humans. Specific details regarding its distribution and biology remain poorly documented in available literature.
Pantolytini
Pantolytini is a tribe of parasitoid wasps in the family Diapriidae. The tribe contains genera such as Acanopsilus, with species distributed in Africa. A 2023 taxonomic revision synonymized the monotypic genus Masnerosema with Acanopsilus and provided an updated diagnosis for the tribe.
Paracharactus
Paracharactus is a genus of sawflies in the family Tenthredinidae, subfamily Blennocampinae. The genus contains at least two described species: P. gracilicornis and P. hyalinus. It is recorded from northern Europe including Denmark, Norway, and Sweden. As a member of the subfamily Blennocampinae, it belongs to a group of sawflies often associated with herbaceous vegetation.
Paracharactus rudis
Paracharactus rudis is a species of sawfly in the family Tenthredinidae, first described by Norton in 1861. It belongs to a genus of sawflies whose members are associated with woody plants. The species is recorded from multiple provinces across Canada including Manitoba, Nova Scotia, Ontario, and Quebec. Sawflies in this family are herbivorous in the larval stage, with many species being economically significant pests of trees and shrubs.
Paracraspis patelloides
Bowl Gall Wasp
Paracraspis patelloides, commonly known as the Bowl Gall Wasp, is a species of cynipid wasp that induces distinctive gall formation on host plants. First described by Trotter in 1910 under the genus Andricus, it was later transferred to Paracraspis. The species is part of the diverse Cynipidae family, which contains numerous gall-inducing wasps primarily associated with oaks and related plants. Observations suggest it is moderately well-documented, with over 100 records on iNaturalist.
Paracyphononyx funereus
Paracyphononyx funereus is a species of spider wasp in the family Pompilidae, first described by Lepeletier in 1845. It belongs to a genus known for koinobiont ectoparasitoid behavior, where females lay eggs on paralyzed spiders that remain mobile until the larva reaches its final developmental stage. The species is part of a group of spider wasps that exhibit diverse host manipulation strategies. Specific biological details for P. funereus remain poorly documented in available literature.
Parahormius
Parahormius is a genus of parasitoid wasps in the subfamily Hormiinae of Braconidae. Members are known to attack pupal stages of Lyonetiidae (Lepidoptera). The genus was established by Nixon in 1940 and contains species distributed across India, the Palearctic region, and the Russian Far East.
Paramesius
Paramesius is a genus of minute parasitoid wasps in the family Diapriidae (order Hymenoptera). These insects are part of the diverse assemblage of proctotrupoid wasps that develop as parasitoids of other insects. The genus has been documented in northern Europe, with records from Denmark, Norway, and Sweden. Members of Diapriidae are generally associated with decaying organic matter where their hosts occur.
Parancistrocerus pensylvanicus
Pennsylvania mason wasp
Parancistrocerus pensylvanicus is a solitary mason wasp in the subfamily Eumeninae. It is a cavity-nesting species that provisions nests with paralyzed caterpillars as food for its larvae. The species has been documented in the northeastern United States, including Vermont. Like other members of its genus, it is difficult to distinguish from closely related species such as Stenodynerus without microscopic examination.
Parania
Parania is a genus of ichneumonid wasps described by Morley in 1913. Species in this genus function as parasitoids of moth larvae. Parania geniculata has been documented as a parasitoid of Homadaula anisocentra, a plutellid moth that defoliates Albizia trees. The genus has limited observation records and appears to be rarely collected.
Paranomada velutina
Black-velvet Flat-Nomad
Paranomada velutina is a cuckoo bee in the family Apidae, described by Linsley in 1939. It belongs to the subfamily Nomadinae, a group of bees that are cleptoparasites (nest parasites) of other bees. The species is known from the southwestern United States and Mexico. Like other nomadine bees, it lacks pollen-collecting structures and relies on host bees to provision its young.
Paratiphia robusta
Paratiphia robusta is a species of wasp in the family Tiphiidae, a group of solitary wasps known for their parasitoid relationships with scarab beetle larvae. The genus Paratiphia belongs to a family whose members are typically ground-nesting and exhibit host-specific parasitism. Limited published information exists specifically for this species, with most knowledge derived from broader family-level characteristics and sparse collection records. The species has been documented through a small number of observations, suggesting it may be uncommon or underreported.
Paratiphia texana
Paratiphia texana is a species of wasp in the family Tiphiidae, first described by Cameron in 1907. The genus Paratiphia comprises parasitic wasps within the Aculeata, a group characterized by stingers derived from modified ovipositors. Like other tiphiid wasps, this species likely functions as a parasitoid, though specific host associations remain poorly documented. The species epithet 'texana' suggests a connection to Texas, possibly indicating the type locality or primary region of occurrence.
Paratrechina longicornis
Longhorn Crazy Ant, Black Crazy Ant
Paratrechina longicornis, commonly known as the longhorn crazy ant or black crazy ant, is a small dark-colored ant species in the family Formicidae. It is one of the most widely distributed ant species globally, found in nearly every tropical and subtropical location through human-mediated transport. The species exhibits remarkable adaptability to human-modified environments, thriving in urban centers, greenhouses, and buildings even in temperate climates. Its erratic, non-linear movement patterns earned it the common name 'crazy ant'. The species is considered one of the world's worst invasive ant species due to its ecological and economic impacts.