Endoparasite
Guides
Acanthocephala
thorny-headed worms, spiny-headed worms, acanthocephalans
Acanthocephala is a phylum of obligate endoparasitic worms known as thorny-headed or spiny-headed worms, characterized by an eversible proboscis armed with recurved hooks used to attach to host intestinal walls. They lack a mouth and digestive system, absorbing nutrients directly through their tegument. The phylum contains approximately 1,200–1,420 described species with complex life cycles involving arthropod intermediate hosts and vertebrate definitive hosts. Recent molecular evidence indicates they are highly modified rotifers, now sometimes classified within Syndermata or Rotifera.
Acrocera
small-headed flies
Acrocera is a genus of small-headed flies in the family Acroceridae. These flies are endoparasitoids of spiders, with larvae developing internally within arachnid hosts. The genus is one of the most species-rich in North America and includes regionally rare species such as A. orbiculus. Adults are rarely encountered due to their brief lifespans and elusive behavior.
Anthracinae
bee flies
Anthracinae is a subfamily of bee flies (family Bombyliidae) comprising more than 80 genera and at least 380 described species. The subfamily includes well-known genera such as Anthrax and Hyperalonia, many of which are parasitoids of other insects. Larval stages are typically endoparasites or ectoparasites of soil-dwelling hosts including tiger beetles, ground-nesting bees, and wasps. Adult flies are often bee-mimics in appearance and are commonly observed hovering or feeding at flowers.
Atrusca unica
Atrusca unica is a species of cynipid gall wasp in the family Cynipidae. Like other gall wasps, it induces the formation of specialized plant structures called galls on its host plant. The genus Atrusca is known for producing colorful, prominent leaf galls on oaks (Quercus spp.). This species appears to be relatively well-documented with 227 observations on iNaturalist, suggesting it is not exceptionally rare, though specific details about its biology remain limited in the provided sources.
Baryscapus
Baryscapus is a genus of parasitoid wasps in the family Eulophidae. Species are endoparasitic, developing within the bodies of other insects. Host associations span multiple insect orders including Hemiptera, Neuroptera, Coleoptera, Lepidoptera, Diptera, and Hymenoptera. Some species are important biological control agents, particularly against agricultural and forestry pests.
Biosteres
Biosteres is a genus of parasitoid wasps in the family Braconidae, first described by Förster in 1862. Species in this genus are solitary or gregarious endoparasitoids, primarily attacking larvae of tephritid fruit flies. Several species, including B. longicaudatus, B. arisanus, and B. tryoni, have been extensively studied for their use in biological control programs against economically important fruit pests. The genus has an almost cosmopolitan distribution, with species documented across Europe, Asia, North America, and other regions.
Caenocholax
Caenocholax is a genus of twisted-winged insects (Strepsiptera) in the family Myrmecolacidae, comprising approximately nine described species. Members are endoparasitoids of ants, with documented associations including Solenopsis invicta and Camponotus planatus. The genus exhibits the extreme sexual dimorphism characteristic of Strepsiptera: males are free-living with reduced forewings and large fan-shaped hindwings, while females remain endoparasitic and neotenic within the host.
Caenocholax fenyesi
Caenocholax fenyesi is a strepsipteran parasitoid in the family Myrmecolacidae, notable for extreme sexual dimorphism and heterotrophic heteronomy—males and females occupy different hosts throughout their life cycles. Females are endoparasites of Orthoptera, while males parasitize ant larvae and pupae, primarily Solenopsis invicta (red imported fire ant) in the United States and related native fire ants in Mexico, Central America, and parts of South America. The species has a sporadic distribution across the southern United States, Central America, and South America, with three recognized cryptic subspecies that are morphologically similar but genetically distinct. Adult males are free-living with a lifespan of only hours to a few days, severely constraining dispersal and contributing to genetic bottlenecking effects.
Cephalops
A genus of small flies in the family Pipunculidae with cosmopolitan distribution. Species are known to be endoparasitoids of planthoppers (Hemiptera: Delphacidae). Adult females locate hosts by detecting substrate-borne vibrations produced by host calls. The genus contains over 150 described species, with new species continuing to be described from under-sampled regions.
Cuterebra fontinella grisea
Cuterebra fontinella grisea is a subspecies of New World skin bot fly (family Oestridae) that parasitizes small mammals, particularly white-footed mice (Peromyscus leucopus). The larvae develop subcutaneously in the host, forming large warbles that can reach 5% of the host's body weight. Despite the conspicuous nature of these parasitic infections, studies indicate that infected mice may actually live longer than non-infected individuals, suggesting a relatively benign host-parasite relationship attributed to long evolutionary co-adaptation. Adults are short-lived, lack functional mouthparts, and are rarely encountered in the field.
Cuterebra tenebriformis
Elasmosoma
Elasmosoma is a small genus of ant-parasitoid wasps in the family Braconidae, subfamily Euphorinae, tribe Neoneurini. Species are minute, typically under 2.0 mm in length, and are specialized endoparasites of adult Formicidae ants. Females attack host workers in flight, alighting briefly to oviposit into the abdomen. The genus comprises approximately 13 described species distributed across the Northern Hemisphere, with records from Europe, Asia, and North America. The host-parasite association represents a well-balanced system that has persisted for at least 40 million years.
Elenchus
Planthopper Twistwing Parasites
Elenchus is a genus of parasitic insects in the family Elenchidae, order Strepsiptera. These insects are commonly known as planthopper twistwing parasites, reflecting their host associations and their membership in the twisted-wing parasite group. The genus was established by Curtis in 1831. Strepsipterans in this genus exhibit the extreme sexual dimorphism characteristic of the order: adult males are free-living with reduced wings and halteres, while females are endoparasitic and remain within their hosts.
Eupathocera
Eupathocera is a genus of twisted-wing parasites in the order Strepsiptera, family Xenidae. Currently considered a synonym of Paraxenos, species historically placed in this genus are obligate endoparasites of insects. As with other strepsipterans, they exhibit extreme sexual dimorphism and complex life cycles involving host manipulation.
Eupathocera auripedis
Eupathocera auripedis is a species of twisted-wing parasite in the order Strepsiptera, family Xenidae. As an obligate endoparasite, it infects host insects and completes its life cycle within their bodies. The species has been documented parasitizing the grass-carrying wasp Isodontia mexicana. Like other strepsipterans, it exhibits extreme sexual dimorphism and complex life history traits associated with its parasitic lifestyle.
Eupathocera erynnidis
Eupathocera erynnidis is a species of twisted-wing parasite in the family Xenidae. It is an obligate endoparasite of insects, with females remaining permanently within host abdomens while males develop to a free-flying adult stage. The species has been documented in North America, including Florida. Like other strepsipterans, it exhibits extreme sexual dimorphism and complex life history adaptations associated with parasitism.
Eupathocera lugubris
Eupathocera lugubris is a species of twisted-wing parasite (order Strepsiptera) in the family Xenidae. The species was originally described by Pierce in 1908 and is currently treated as a synonym of Paraxenos lugubris. Strepsipterans are obligate endoparasites of other insects, with this species likely parasitizing wasps or related hosts. The genus is part of the diverse and complex parasitic wasp-associated Strepsiptera fauna of North America.
Eupathocera westwoodii
Eupathocera westwoodii is a species of twisted-wing parasite in the order Strepsiptera. These insects are obligate endoparasites of other insects, with larvae entering hosts through joints or sutures. The species has been documented parasitizing wasps, including the Great Black Wasp (Sphex pensylvanicus). Females are neotenic and remain permanently within host abdomens, while males emerge as free-flying adults that live only a few hours and must mate within that brief window.
Exorista
uzi fly
Exorista is a genus of tachinid flies comprising approximately 70 described species distributed across multiple subgenera. The genus includes both beneficial biocontrol agents and economically significant pests of sericulture. Species such as E. sorbillans (uzi fly) are major constraints on silk production, causing up to 80% crop loss in outdoor silkworm operations through endoparasitic larval development. Other species have been evaluated for biological control of agricultural pests, including E. larvarum for in vitro rearing and E. deligata for control of tea loopers. The genus exhibits diverse host associations, primarily targeting Lepidoptera.
Exorista larvarum
Exorista larvarum is a Palaearctic tachinid fly and polyphagous larval endoparasitoid of Lepidoptera. The species was introduced to North America in the 20th century for biological control of the gypsy moth (Lymantria dispar). It is notable for being one of the few parasitoids that can be efficiently reared from egg to adult on artificial diets without living hosts, making it a promising candidate for mass production in augmentative biological control programs.
Exoristini
Exoristini is a tribe of flies within the family Tachinidae, subfamily Exoristinae. The tribe contains approximately 22 genera, including the type genus Exorista Meigen, 1803. Members are parasitoid flies, with larvae typically developing inside other insects. The tribe is distinguished from related tachinid tribes by morphological features of the male terminalia and larval cephalopharyngeal skeleton. Exoristini has a cosmopolitan distribution, with species found across multiple continents.
Glyptapanteles
Glyptapanteles is a genus of koinobiont endoparasitoid wasps in the family Braconidae, distributed across all continents except Antarctica. Species in this genus are distinguished by their ability to manipulate host behavior: after larval emergence from caterpillar hosts, the paralyzed host remains near the pupal cocoons and defends them against predators through violent thrashing movements. This behavioral manipulation is mediated by one or two larvae that remain within the host and sacrifice their own development to protect their siblings. Several species have been evaluated for biological control of lepidopteran pests, particularly Lymantria dispar.
Halictophagidae
Halictophagidae is a family of twisted-wing parasites (Strepsiptera) comprising at least eight genera including Halictophagus, Coriophagus, and Dipterophagus. Members are endoparasitoids of other insects, with documented host associations including leafhoppers (Cicadellidae). The family has a cosmopolitan distribution through genus Halictophagus, while genus Coriophagus shows a Gondwanan distribution pattern with records from Africa, Australia, New Zealand, Solomon Islands, India, and Brazil.
Halictophagus
Leafhopper Twistwing Parasites
Halictophagus is a genus of twisted-wing parasites (Strepsiptera) in the family Halictophagidae. These insects are endoparasitoids of leafhoppers and related Hemiptera, primarily in the families Cicadellidae and Cercopidae. The genus exhibits extreme sexual dimorphism: free-living males with reduced wings and branched antennae, and neotenic females that remain within the host. Multiple species have been described worldwide, with documented hosts including mango leafhoppers (Idioscopus spp., Bakera nigrobilineata) and other planthoppers.
Halictoxenos
Halictoxenos is a genus of strepsipteran insects (twisted-wing parasites) in the family Stylopidae. The genus comprises approximately 23 species distributed across Asia, Europe, Africa, and the Americas, with a primarily Holarctic distribution. All species are obligate endoparasites of bees in the family Halictidae, particularly the subfamily Halictinae. The genus was established by W. Dwight Pierce in 1909.
Hypoderma
Warble Flies, Heel Flies, Bomb Flies, Gadflies
Hypoderma is a genus of large parasitic flies in the family Oestridae, commonly known as warble flies. Adults are non-feeding and live only to reproduce. Females deposit eggs on the legs and flanks of cattle and other ungulates; first-instar larvae penetrate the skin and migrate through the host's body, typically to the gullet or spinal canal, before settling in subcutaneous tissues of the back to develop. The larvae create characteristic swellings (warbles) visible on the host's hide. Two economically important species are H. bovis (ox warble fly) and H. lineatum (cattle warble fly), which cause significant damage to cattle hides and reduce animal welfare.
Leionotoxenos
Leionotoxenos is a genus of twisted-wing parasitoids in the family Xenidae. It was described by Pierce in 1909 and is currently treated as a synonym of Pseudoxenos. Members of this group are endoparasites of other insects, with females remaining larval and neotenic throughout their lives. The genus is part of the highly modified and morphologically unusual order Strepsiptera.
Leionotoxenos tigridis
Leionotoxenos tigridis is a species of twisted-wing parasitoid in the family Xenidae. The species was originally described as Pseudoxenos tigridis by Pierce in 1911 and later transferred to the genus Leionotoxenos. It is known from a small number of observations in North America, particularly from Illinois. As with all Strepsiptera, this species is an endoparasitoid of other insects.
Miastor
Miastor is a genus of gall midges and wood midges in the family Cecidomyiidae, comprising approximately seven described species. The genus is notable for exhibiting paedogenesis, a rare reproductive strategy in which larvae reproduce parthenogenetically without metamorphosing into adults. Multiple asexual generations can occur before adults eventually develop. Larvae have been recorded in diverse habitats including fungal fruiting bodies, dung, tree bark, and decaying plant matter.
Oestrinae
Nose Bot Flies
Oestrinae is a subfamily of bot flies (Oestridae) comprising 9 genera and 34 species of obligate mammalian parasites. Larvae develop within the nasal, pharyngeal, and frontal cavities of deer, sheep, and related ungulates, feeding on cellular debris and mucosal secretions. Adult females are larviparous, depositing live larvae directly into host nostrils. The subfamily includes economically significant pests of livestock and game animals.
Peleteria
Peleteria is a widespread genus of tachinid flies (Diptera: Tachinidae) comprising approximately 100 described species distributed across multiple continents. Members of this genus are larval endoparasitoids of various insect hosts, including caterpillars and other herbivorous insects. The genus is taxonomically divided into several subgenera based on morphological characters. Peleteria species contribute to natural biological control of agricultural and forest pests.
Phobocampe
Phobocampe is a genus of ichneumonid wasps in the subfamily Campopleginae. Species are solitary endoparasitic koinobiont parasitoids of lepidopteran larvae. P. confusa is a specialist on Nymphalini butterflies in Europe, particularly Aglais species, and represents a significant mortality factor for these host populations. P. tempestiva parasitizes the winter moth Operophtera brumata in northern Scotland.
Pipunculinae
big-headed flies
Pipunculinae is a subfamily of big-headed flies within the family Pipunculidae. It comprises approximately 9 genera and at least 130 described species. Members are parasitoids, primarily attacking leafhoppers and planthoppers (Auchenorrhyncha). The subfamily is divided into five tribes: Cephalopsini, Microcephalopsini, Eudorylini, Tomosvaryellini, and Pipunculini.
Protocalliphora bennetti
Protocalliphora bennetti is a species of blow fly in the family Calliphoridae, described by Whitworth in 2002. The genus Protocalliphora comprises nest parasites of birds, with larvae developing in the blood of nestling birds. This species is one of approximately 20 recognized species in the genus, which are distributed primarily in the Holarctic region. Like congeners, P. bennetti likely exhibits the characteristic life history of bird nest parasitism that defines the genus.
Rhipiceridae
Cicada-Parasite Beetles
Rhipiceridae is a family of beetles specialized as parasitoids of cicada nymphs. Larvae exhibit hypermetamorphosis, with mobile planidial first instars that actively locate and penetrate underground cicada nymphs, developing as endoparasitoids until host death. Adults display pronounced sexual dimorphism: males possess large flabellate antennae with approximately 30,000 sensilla placodea for detecting chemical cues, while females have compact bodies with simple antennae bearing around 100 sensilla. The family comprises seven genera and approximately 100 described species divided into two subfamilies: Rhipicerinae (Australia, New Caledonia, Chile) and Sandalinae (Americas, Africa, Europe, Asia).
Speleognathinae
Speleognathinae is a subfamily of mites in the family Ereynetidae comprising endoparasites of the respiratory tracts of birds. These mites inhabit the nasal cavities and associated passages of avian hosts across multiple continents. At least 37 species in 15 genera have been documented from the Afrotropical region alone. The subfamily is distinguished from related nasal mite taxa by morphological features used in taxonomic keys.
Strepsiptera
Twisted-wing Insects, Twisted-wing Parasites, Stylops
Strepsiptera is an order of obligate endoparasitic insects comprising approximately 600 described species across 11 extant families. The group exhibits extreme sexual dimorphism: males are free-living, short-lived adults with reduced forewings modified into halteres and large fan-shaped hindwings, while females are neotenic, larviform, and remain permanently within their insect hosts. All strepsipterans are parasites of other insects, with documented hosts spanning seven orders including Hymenoptera, Hemiptera, Orthoptera, Blattodea, Mantodea, Zygentoma, and Diptera. The order is believed to be most closely related to Coleoptera, forming the clade Coleopterida.
Stylops
stylops
Stylops is a genus of obligately endoparasitic insects in the family Stylopidae, order Strepsiptera. Members are endoparasites of Hymenoptera, particularly bees in the family Andrenidae. The genus exhibits extreme sexual dimorphism: males are free-living with wings and functional limbs, while females are neotenic, legless, and remain permanently embedded within host abdomens with only the cephalothorax protruding. The genus has cosmopolitan distribution with numerous described species, though taxonomic status of many remains problematic due to reliance on poor female morphological characters.
Thecophora propinqua
Thecophora propinqua is a species of thick-headed fly in the family Conopidae, described by Adams in 1903. As a member of this family, it is likely an endoparasitoid of other insects, particularly bees or wasps, which is the characteristic life history of conopid flies. The genus Thecophora contains multiple species distributed across North America.
Winthemia
Winthemia is a genus of tachinid flies (Diptera: Tachinidae) comprising over 100 described species distributed worldwide. Species in this genus are parasitoids of Lepidoptera, with larvae developing internally in host caterpillars. Several species have been studied as biological control agents of agricultural pests, including W. rufopicta on Heliothis species, W. fumiferanae on spruce budworm, and W. manducae on tobacco hornworm. The genus exhibits protandry in adult emergence and shows complex interactions with host populations.
Xenidae
twisted-wing parasites
Xenidae is a family of endoparasitic twisted-wing insects (Strepsiptera) comprising approximately 13 genera and over 120 described species. Members are obligate endoparasites primarily of social wasps and hornets (Hymenoptera: Vespidae), though some genera parasitize other wasp families including Sphecidae and Bembicidae. The family exhibits extreme sexual dimorphism: males are free-living with reduced forewings and functional hindwings, while females are neotenic, legless, and permanently embedded within their hosts with only a cephalothorax protruding. Molecular studies indicate substantial cryptic species diversity, with actual species numbers likely at least double current descriptions.
Xenos
twisted-wing parasites
Xenos is a genus of twisted-wing parasites in the order Strepsiptera. These insects are obligate endoparasites of other insects, with larvae entering hosts through joints or sutures. Adult males are free-flying and short-lived, while neotenic females remain permanently within host abdomens. The genus includes species such as Xenos peckii, which parasitizes wasps including Polistes fuscatus.
Xenos bicolor
Xenos bicolor is a species of twisted-wing parasite in the family Xenidae, order Strepsiptera. Like other strepsipterans, it is an obligate endoparasite that develops within the bodies of host insects. The genus Xenos is known to parasitize wasps, particularly paper wasps in the family Vespidae. Strepsipterans exhibit extreme sexual dimorphism and reduced morphology, with neotenic females remaining permanently embedded in host abdomens.
Xenos peckii
Xenos peckii is a highly specialized endoparasitic insect in the order Strepsiptera, commonly known as twisted-wing parasites. It is an obligate parasite of paper wasps, specifically Polistes fuscatus, with development occurring entirely within the host's abdominal cavity. The species exhibits extreme sexual dimorphism: males are free-flying adults with reduced wings and unusual eyes containing green- and UV-sensitive photoreceptors, while females are neotenic, lacking wings, legs, and eyes, and remain permanently embedded within the host. Males locate females through a species-specific sex pheromone, (3R,5S,9R,7E,11E)-3,5,9,11-tetramethyl-7,11-tridecadienal, which females actively release by inflating and extruding their cephalothorax through the host's cuticle. The species has been documented across temperate North America and possesses unique cellular mechanisms for meiotic spindle formation that have been studied ultrastructurally.