Conopidae

Conopids can be distinguished from similar-looking wasps and bees by their single pair of wings ( Diptera characteristic) and reduced hindwings modified as halteres. They differ from syrphid flies by their broad head, often geniculate proboscis, and wing venation including a closed anal cell and very long first basal cell. The presence of an inflatable ptilinum above the antennae is diagnostic. Stylogaster species are immediately recognizable by their highly elongated, needle-like female abdomen. Within the family, subfamilies can be distinguished by ocelli presence (Conopinae have ocelli, Myopinae lack them) and tibial bristles (Myopinae have dorsal preapical bristle, others do not). Genera such as Physocephala and Physoconops resemble potter wasps with elongated abdomens and pigmented wing margins, while Conops and Myopa have different body proportions.

Adult conopids are small to large flies ranging from 3–20 mm (usually 5–15 mm), with a characteristically broad head that gives the family its common name. The body is rather thinly pilose or nearly bare, elongate or stout, often lustrous with black and yellow or black and white color patterns, sometimes with reddish brown markings. Many species strikingly resemble wasps, bees, or syrphid flies. The frons is broad in both sexes. Ocelli may be present or absent depending on subfamily. Antennae have three segments, with the third bearing a dorsal bare arista or terminal style; an inflatable ptilinum is present above the antennae. The proboscis is long, slender, and often geniculate (elbowed). The wing is usually clear, sometimes with dark markings along the costa; wing venation includes a continuous costa, complete subcostal vein, closed anal cell, and a very long first basal cell. The base of the abdomen is often constricted, and female genitalia are frequently large or greatly elongated. Tibiae may have dorsal preapical bristles in some subfamilies.

Conopids are found in diverse terrestrial habitats worldwide, excluding polar regions and many Pacific islands. Adults are most frequently encountered at flowers, particularly where their hymenopteran hosts forage. Larval habitat is determined by host availability, as all larvae develop internally within aculeate Hymenoptera hosts. Some Stylogaster species are associated with army ant colonies in tropical regions, though this association is not obligatory for all species in the genus.

Worldwide distribution across all biogeographic realms except the poles and many Pacific islands. Approximately 70 species occur in North America. The genus Stylogaster is most diverse in the Neotropics, sub-Saharan Africa, and Southeast Asia, with only two species in North America. The family is represented in Colombia by 16 species in four genera, with Stylogaster being the richest group in that region. In Europe, several Myopa species are common in early spring among Salix catkins.

Adult activity varies by genus and region. Myopa species are commonly observed in early spring in Europe, flying among Salix catkins with their Andrena hosts. Many conopid species appear to have single generations per year in temperate regions, with adults emerging in summer. In southern climates, some Physocephala species may have more than one generation annually. Stylogaster neglecta has been documented in August in Missouri.

Adults feed exclusively on nectar using their long, slender, often geniculate proboscis. They are frequent visitors to flowers and have been observed scraping labellum on fungal surfaces. Larvae are internal parasitoids that consume host tissues from within aculeate Hymenoptera hosts, eventually killing the host.

• Aculeata (stinging Hymenoptera) - primary hostLarvae are internal parasitoids of wasps and bees; most conopid species utilize this host group
• Bombus terrestris and other bumblebees - hostVulnerable foraging bees are most susceptible to parasitism; Physocephala species are known parasites
• Andrena (mining bees) - hostMyopa species are associated with Andrena hosts; M. pellucida confirmed in A. nitida, M. hirsuta and M. testacea in A. vaga, M. vicaria in A. regularis
• Ceratina (small carpenter bees) - hostPhysocephala tibialis has been observed parasitizing this host
• Bembix (sand wasps) - hostPhysocephala texana is a known parasite of several Bembix species
• Solitary wasps - hostZodion species attack solitary wasps
• Crickets, cockroaches, calyptrate flies - hostStylogaster species are obligate parasites of these groups, not aculeate Hymenoptera
• Army ants (Ecitoninae, Dorylinae) - mutualismSome Stylogaster species are obligate associates, using ant raiding columns to flush prey; however, this is not obligatory for all Stylogaster species as the genus occurs in Madagascar and Africa where army ants are absent

The life cycle involves internal parasitism of host Hymenoptera. Adult females aggressively intercept hosts in flight, using a modified abdomen described as a 'can opener' to pry open host abdominal segments and insert eggs. In Stylogastrinae, eggs are harpoon-shaped with rigid barbed tips and are forcibly jabbed into hosts. Larvae hatch and develop as endoparasitoids within the living host, consuming host tissues over approximately 10–12 days before killing the host. The mature larva pupates inside the hollow host exoskeleton. Some Physocephala species induce behavioral changes in hosts—P. tibialis causes infected bumblebees to bury themselves before death, allowing adult fly emergence underground. Adults typically emerge the following summer, though some southern populations may have multiple generations. Overwintering occurs as pupae within host remains.

Adult females exhibit aggressive host-seeking behavior, actively pursuing aculeate Hymenoptera in flight to force oviposition. This mid-air interception may involve grappling with the host and forcing it to the ground. Adult conopids are rapid, nervous fliers that are difficult to approach. Both sexes visit flowers for nectar, with some species showing fidelity to particular floral resources associated with host activity. Males are not involved in host parasitism. Some Stylogaster species demonstrate association with army ant swarms, exploiting the disturbance to locate hosts.

Conopids function as significant parasitoids regulating populations of aculeate Hymenoptera, particularly bees and wasps. They exert substantial selective pressure on host populations, with infected colonies showing reduced ability to produce sexual offspring in late summer. The family has documented negative impacts on pollinator populations, especially bumblebees, with potential economic implications for honey bee colonies attacked by Physocephala species. Adult flower-visiting behavior contributes to pollination, though this is incidental to their nectar-feeding. As parasitoids, they represent an important trophic link between floral resources and higher predators.

Certain Physocephala species have minor economic importance as parasites of honey bees. The family has been studied for its impacts on native pollinator populations, with concerns about parasitoid-induced declines in bumblebee colonies. Conopids are of interest in biological control research and parasitoid-host evolutionary studies. They are occasionally encountered by entomologists and naturalists at flowers, though their rapid flight and wasp-like appearance make them challenging subjects for observation and photography.

• Syrphidae (hoverflies)Many conopids, particularly Physocephala and Physoconops, strikingly resemble bee-mimicking syrphids in coloration and body form; distinguished by head shape, proboscis structure, wing venation, and single pair of wings
• Vespidae (potter wasps, mason wasps)Conopids in genera Physocephala and Physoconops closely mimic potter wasps with elongated 'wasp-waisted' abdomens and wing folding patterns; distinguished by wing number, head shape, and absence of wasp-like petiole constriction
• Apidae (bees)Black and yellow conopid color patterns mimic bees; distinguished by wing structure, absence of branched body hairs, and head morphology
• Asilidae (robber flies)Both families include predatory/parasitic flies with robust bodies; distinguished by conopid head shape, proboscis structure, and parasitic versus predatory life history

• parasitoid
• Diptera
• Hymenoptera parasite
• flower visitor
• bee mimic
• wasp mimic
• internal parasite
• endoparasitoid
• pollinator parasite
• aculeate parasite

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Conopidae | Beetles In The Bush
• Bug Eric: Sand Wasps, Genus Bembix
• Bug Eric: April 2011
• Diptera | Beetles In The Bush | Page 8
• Northern Ireland, invertebrate finds in review 2023 - Buglife Blog - Buglife
• Bug Eric: The Mason Wasp Euodynerus foraminatus Endorses Bee Blocks
• Conopidae larvae (Diptera: Conopidae) as endoparasitoids of Aculeata
• FAMILY CONOPIDAE
• Parasitic behavior of the larvae of the Conopidae family (Diptera: Conopidae)
• The evolutionary biology of Conopidae (Diptera) : a life history, molecular, morphological, systematic, and taxonomic approach
• Revision of the Myopa testacea Species-Group in the Palaearctic Region (Diptera: Conopidae)
• First host record of Myopa pellucida Robineau-Desvoidy (Diptera: Conopidae) identified using DNA barcoding 
• Death and diminishment: parasitoid flies (Diptera: Conopidae) reduce foraging efficiency before killing their bumblebee host.