Robber-fly
Guides
Efferia staminea
Straw-faced Hammertail
Efferia staminea is a species of robber fly in the family Asilidae. It has been studied for its predatory behavior, with research documenting how its diet varies temporally and spatially in response to prey availability. The species exhibits opportunistic feeding patterns, shifting prey composition based on local prey abundance—including documented increases in ant predation during mating swarms of Formica subpolita. It serves as a generalist predator in grassland ecosystems.
Efferia subarida
Tucson Hammertail
Efferia subarida is a robber fly species in the family Asilidae, first described by Bromley in 1940. It is commonly known as the Tucson Hammertail and is found in the southwestern United States, particularly Arizona. The species belongs to the diverse genus Efferia, which contains many large, predatory flies characterized by their stout bodies, prominent compound eyes, and powerful flight capabilities. Like other robber flies, E. subarida is an active aerial predator that captures other insects in flight.
Efferia subcuprea
Chiricahua Hammertail
Efferia subcuprea is a species of robber fly (family Asilidae) described by Schäffer in 1916. The species belongs to the genus Efferia, a large and diverse group of predatory flies distributed primarily in the New World. The common name "Chiricahua Hammertail" suggests an association with the Chiricahua region of southeastern Arizona. Robber flies in this genus are generally characterized by their robust build, strong predatory habits, and often distinctive sexual dimorphism, with males typically possessing a swollen terminal abdominal segment.
Efferia subpilosa
Efferia subpilosa is a species of robber fly in the family Asilidae, first described by Schäffer in 1916. The genus Efferia comprises medium to large-sized predatory flies distributed primarily in the New World, with many species occurring in arid and semi-arid regions of North and South America. Members of this genus are characterized by their robust build, prominent compound eyes, and predatory habits. Efferia subpilosa is one of numerous species within this diverse genus, though specific ecological and behavioral details remain poorly documented in the available literature.
Efferia tabescens
Sesqui Hammertail
Efferia tabescens is a species of robber fly (family Asilidae) described by Nathan Banks in 1919. The common name "Sesqui Hammertail" refers to this species. Robber flies in the genus Efferia are predatory insects that capture other insects in flight. The species has been documented through 143 iNaturalist observations, indicating it is moderately well-recorded in citizen science databases. As a member of the Asilidae, it shares the family's characteristic predatory behavior and robust body form adapted for aerial hunting.
Efferia tagax
Arizona Club-legged Hammertail
Efferia tagax is a robber fly species in the family Asilidae, first described by Williston in 1885. It occurs in the southwestern United States, particularly Arizona, where it has been recorded at mercury-vapor lights in juniper chaparral habitat. The species belongs to a diverse genus of predatory flies commonly known as club-legged hammertails. Like other Efferia species, it likely exhibits typical robber fly predatory behavior, ambushing and capturing other insects in flight.
Efferia texana
Texas Hammertail
Efferia texana is a species of robber fly in the family Asilidae, commonly known as the Texas Hammertail. This predatory fly is native to southwestern North America and belongs to a diverse genus of aerial predators that hunt other insects. The species was first described by Banks in 1919 and is recognized as a valid taxon in major databases including GBIF and Catalogue of Life.
Efferia tolandi
Efferia tolandi is a species of robber fly (family Asilidae) described by Wilcox in 1966. The genus Efferia comprises medium to large-sized predatory flies found primarily in arid and semi-arid regions of North America. Members of this genus are characterized by their robust build, large compound eyes, and predatory habits. Efferia species are often encountered at light traps and are active predators of other insects.
Efferia tricella
Silver Hammertail
Efferia tricella is a species of robber fly in the family Asilidae, commonly known as the Silver Hammertail. Robber flies in the genus Efferia are predatory insects known for their robust build, large eyes, and aggressive hunting behavior. The species was described by Bromley in 1951. Like other Asilidae, it is presumed to be an aerial predator that captures other insects in flight.
Efferia triton
Triton Hammertail
Efferia triton is a species of robber fly in the family Asilidae, commonly known as the Triton Hammertail. Like other robber flies, it is an aerial predator that captures prey in flight. The species belongs to the large and diverse genus Efferia, which contains numerous species across North America. Specific ecological details for E. triton remain limited in published sources.
Efferia tuberculata
Thorny Hammertail
Efferia tuberculata is a species of robber fly in the family Asilidae, commonly known as the Thorny Hammertail. The species was described by Coquillett in 1904. Robber flies in the genus Efferia are predatory insects known for their robust build and distinctive genital structures in males. Like other Asilidae, they are aerial predators that capture other insects in flight.
Efferia tucsoni
Reddish Thorny Hammertail
Efferia tucsoni is a species of robber fly (family Asilidae) described by Wilcox in 1966. The common name 'Reddish Thorny Hammertail' refers to distinctive morphological features typical of the genus. Robber flies in the genus Efferia are predatory dipterans known for their aggressive hunting behavior and distinctive genital capsule morphology in males. The species is part of a large North American genus that has undergone taxonomic revision, with some former Efferia species now placed in related genera such as Triorla.
Efferia varipes
Colorado Hammertail
Efferia varipes is a species of robber fly in the family Asilidae, commonly known as the Colorado Hammertail. The species belongs to the large and diverse genus Efferia, which contains numerous species across North and South America. Robber flies in this genus are predatory insects that capture other insects in flight. The specific epithet 'varipes' refers to variable legs, suggesting some morphological variation in this character.
Efferia vertebrata
Mountain Hammertail
Efferia vertebrata is a species of robber fly (family Asilidae) first described by Bromley in 1940. Known by the common name "Mountain Hammertail," this predatory dipteran belongs to the large and diverse genus Efferia, which contains numerous species distributed primarily in the Americas. Robber flies in this genus are characterized by their robust build, strong flying ability, and predatory habits. The specific epithet "vertebrata" likely refers to some aspect of the species' structural morphology, though the precise meaning is not documented in readily available sources.
Efferia wilcoxi
Wilcox Hammertail
Efferia wilcoxi is a species of robber fly in the family Asilidae, described by Bromley in 1940. The species belongs to the genus Efferia, a large and diverse group of predatory flies commonly known as "hammertails" due to the swollen genital capsule in males. As a member of the subfamily Dasypogoninae, this species exhibits the characteristic predatory behavior and morphology typical of robber flies, including large compound eyes, a concave face with a mystax of bristles, and raptorial legs adapted for capturing prey in flight. The specific epithet "wilcoxi" honors an individual, likely an entomologist or collector associated with the type specimen.
Efferia willistoni
Williston Hammertail
Efferia willistoni is a species of robber fly in the family Asilidae, commonly known as the Williston Hammertail. It is one of approximately 200 species in the genus Efferia, a diverse group of predatory flies distributed primarily in the Americas. The species was described by Hine in 1919. As with other asilids, it is presumed to be an active aerial predator of other insects.
Efferia yuma
Efferia yuma is a species of robber fly in the family Asilidae, described by Wilcox in 1966. Robber flies in the genus Efferia are among the largest and most charismatic members of the family, often recognized by their impressive size, striking green eyes in males, and predatory habits. The species name "yuma" likely refers to the Yuma region of southwestern Arizona or adjacent California, suggesting an association with arid southwestern habitats. Members of this genus are aerial predators that capture other insects in flight.
Efferia zonata
Banded Hammertail
Efferia zonata is a species of robber fly (family Asilidae) described by Hine in 1919. The species belongs to the Efferia group, a lineage of large, predatory flies formerly treated as a subgenus of Efferia but now widely regarded as comprising valid related genera including Triorla. As a member of this group, E. zonata likely shares characteristics with other large, powerful predatory flies that actively hunt other insects. The specific epithet 'zonata' suggests banded coloration patterning.
Eucyrtopogon albibarbus
Eucyrtopogon albibarbus is a species of robber fly in the family Asilidae, described by Curran in 1923. The genus Eucyrtopogon contains small to medium-sized predatory flies that can be confused with the related genus Comantella. Both genera share traits such as early spring and late fall adult activity, a humpbacked profile, and ground-perching behavior in open habitats.
Eucyrtopogon calcaratus
Eucyrtopogon calcaratus is a species of robber fly in the family Asilidae, described by Curran in 1923. It belongs to a genus of predatory flies known for their aerial hunting behavior. The specific epithet "calcaratus" refers to a spur or calcar, likely describing a morphological feature of the legs. The species is part of the diverse robber fly fauna of North America, though detailed biological information appears limited in available sources.
Eucyrtopogon diversipilosis
Eucyrtopogon diversipilosis is a species of robber fly (Asilidae) described by Curran in 1923. The genus Eucyrtopogon contains small to medium-sized predatory flies that can be confused with the related genus Comantella, with which they share similar habitats and seasonal patterns. Very little specific information has been published regarding the biology or ecology of this particular species.
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Eucyrtopogon nigripes
Eucyrtopogon nigripes is a species of robber fly (family Asilidae) described by Jones in 1907. The specific epithet "nigripes" (Latin for "black-footed") suggests a distinctive dark coloration of the legs. Robber flies in the genus Eucyrtopogon are generally small to medium-sized predatory flies. This species belongs to a diverse family of aerial predators known for their hunting behavior.
Eucyrtopogon spiniger
Eucyrtopogon spiniger is a species of robber fly in the family Asilidae, described by Curran in 1923. It belongs to a genus of small, slender robber flies found in North America. Members of this genus are predatory as adults, capturing other insects in flight. The specific epithet 'spiniger' refers to spine-bearing characteristics, likely describing some aspect of the morphology.
Eudioctria
Eudioctria is a genus of small robber flies in the family Asilidae, established by Wilcox & Martin in 1941. The genus comprises approximately 14 described species, making it one of the more species-rich genera within the subfamily Stenopogoninae. Species in this genus are among the smallest North American robber flies, measuring only 6–8 mm in length. The genus is primarily distributed in western North America, though four species extend into eastern states.
Eudioctria albius
Eudioctria albius is a small robber fly species in the family Asilidae, measuring approximately 6–8 mm in length. It is one of four Eudioctria species occurring in eastern North America, with the genus being primarily western in distribution. The species belongs to the subfamily Stenopogoninae and is among the tiniest North American robber flies.
Eudioctria beameri
Eudioctria beameri is a small robber fly in the family Asilidae, subfamily Stenopogoninae. It belongs to a genus containing some of the smallest North American robber flies, with body lengths of only 6–8 mm. The species is primarily western in distribution, though some Eudioctria species extend into eastern North America. Like other robber flies, it is an active aerial predator that captures prey in flight.
Eudioctria brevis
Eudioctria brevis is a small species of robber fly in the family Asilidae, subfamily Stenopogoninae. It is one of four Eudioctria species occurring in eastern North America, with the genus primarily distributed in western United States. The species is among the smallest North American robber flies, measuring 6–8 mm in length. It was described by Banks in 1917.
Eudioctria denuda
Eudioctria denuda is a species of robber fly in the family Asilidae, subfamily Stenopogoninae. It belongs to a genus of small, compact robber flies measuring only 6–8 mm in length. The genus Eudioctria is primarily western in distribution, with only four of its fourteen species occurring in eastern North America. Species identification within the genus requires examination of facial gibbosities and assessment of pollinosity on body parts.
Eudioctria disjuncta
A small robber fly in the subfamily Stenopogoninae, measuring 6–8 mm in length. One of the tiniest North American robber flies, superficially resembling Cerotainia species but distinguished by shorter antennae and behavioral perching preferences. The genus Eudioctria is primarily western in distribution, with E. disjuncta being one of four eastern species.
Eudioctria dissimilis
Eudioctria dissimilis is a species of robber fly in the subfamily Stenopogoninae, described by Adisoemarto and Wood in 1975. The genus Eudioctria comprises some of the smallest North American robber flies, with body lengths of 6–8 mm. Species in this genus are primarily western in distribution, though E. dissimilis is one of four eastern species.
Eudioctria doanei
Eudioctria doanei is a small robber fly (family Asilidae) in the subfamily Stenopogoninae. It belongs to a genus of diminutive predatory flies measuring only 6–8 mm in length, making them among the smallest North American robber flies. The species was described by Melander in 1924. While specific details about this particular species are sparse, the genus Eudioctria is primarily western in distribution, with four of its fourteen species extending into eastern North America. Members of this genus are known to perch on flat leaves at the tops of small shrubs, distinguishing them behaviorally from similar-looking Cerotainia species that prefer twig-ends.
Eudioctria media
Eudioctria media is a species of robber fly in the family Asilidae, subfamily Stenopogoninae. It is one of approximately 14 species in the genus Eudioctria, a group of small predatory flies found primarily in western North America with a few species extending into eastern states. The genus is characterized by extremely small body size among robber flies, measuring only 6–8 mm in length.
Eudioctria monrovia
Eudioctria monrovia is a species of robber fly (family Asilidae, subfamily Stenopogoninae) described by Wilcox and Martin in 1941. The genus Eudioctria comprises some of the smallest North American robber flies, with adults measuring only 6–8 mm in length. Species in this genus are primarily western in distribution, though a few species extend into eastern North America. Like other robber flies, members of this genus are predatory as adults.
Eudioctria nitida
Eudioctria nitida is a species of robber fly in the family Asilidae, subfamily Stenopogoninae. It is one of the smallest North American robber flies, measuring approximately 6–8 mm in length. The genus Eudioctria contains 14 species, with most distributed in the western United States; four species (including E. nitida) extend into eastern North America. Species identification within the genus requires examination of facial gibbosities and pollinosity patterns.
Eudioctria propinqua
Eudioctria propinqua is a species of robber fly in the family Asilidae, subfamily Stenopogoninae. It is among the smallest North American robber flies, measuring approximately 6–8 mm in length. The species occurs in eastern North America and is one of four Eudioctria species found in the eastern United States.
Eudioctria sackeni
Eudioctria sackeni is a species of robber fly in the family Asilidae, subfamily Stenopogoninae. The genus Eudioctria comprises among the smallest North American robber flies, measuring only 6–8 mm in length. Species in this genus superficially resemble Cerotainia (subfamily Laphriinae) but lack the extra-long antennae. Eudioctria is primarily a western U.S. genus, though four of its 14 species occur in eastern states.
Eudioctria unica
Eudioctria unica is a species of robber fly in the family Asilidae, described by Adisoemarto and Wood in 1975. It belongs to the subfamily Stenopogoninae and is among the smallest North American robber flies, measuring only 6–8 mm in length. The genus Eudioctria is primarily western in distribution, with only four species extending into eastern North America.
Hadrokolos
Hadrokolos is a genus of robber flies (Asilidae) established by Martin in 1959. The genus contains at least four described species distributed in North America. As members of the Asilidae family, species in this genus are predatory flies. The genus is relatively small and understudied compared to larger asilid genera.
Hadrokolos cazieri
Hadrokolos cazieri is a species of robber fly in the family Asilidae, first described by Martin in 1959. The genus Hadrokolos is a small group within the diverse asilid fauna of North America. Robber flies in this genus are predatory insects that capture other arthropods in flight. Specific ecological details for H. cazieri remain poorly documented in published literature.
Hadrokolos texanus
Hadrokolos texanus is a species of robber fly in the family Asilidae, first described by Bromley in 1934. The genus Hadrokolos is a relatively small group within the diverse robber fly family. Like other Asilidae, this species is presumably predatory as both adults and larvae, though specific details of its biology remain poorly documented. The specific epithet 'texanus' indicates a type locality or primary association with Texas.
Haplopogon bullatus
Haplopogon bullatus is a species of robber fly in the family Asilidae, described by Bromley in 1934. The genus Haplopogon belongs to the subfamily Stenopogoninae, a group of predatory flies characterized by their elongated bodies and strong predatory habits. Like other asilids, this species is presumed to be an active aerial predator of other insects.
Haplopogon dicksoni
Haplopogon dicksoni is a species of robber fly (family Asilidae) described by Wilcox in 1966. The genus Haplopogon is a small group within the subfamily Asilinae, characterized by reduced wing venation and specific genitalic structures. Species in this genus are poorly documented in published literature, with most information limited to original taxonomic descriptions.
Haplopogon erinus
Haplopogon erinus is a species of robber fly described by Pritchard in 1941. It belongs to the genus Haplopogon, a group within the Asilidae family characterized by reduced wing venation and distinctive predatory habits. The species is known from limited collection records and remains poorly documented in the scientific literature.
Haplopogon triangulatus
Haplopogon triangulatus is a species of robber fly (family Asilidae) described by Martin in 1955. As a member of this predatory fly family, it likely shares the characteristic hunting behavior of ambushing and capturing other insects in flight. The species epithet 'triangulatus' suggests a triangular feature in its morphology, possibly in wing venation or body shape. No iNaturalist observations are recorded for this species, indicating it may be rare, poorly known, or restricted in distribution.
Haplopogon utahensis
Haplopogon utahensis is a species of robber fly (family Asilidae) described by Wilcox in 1966. As a member of the diverse Asilidae family, it is a predatory dipteran. The specific epithet 'utahensis' indicates a connection to Utah, likely reflecting the type locality or known distribution. Robber flies in this genus are typically aerial predators that capture other insects in flight.
Heteropogon arizonensis
Heteropogon arizonensis is a species of robber fly in the family Asilidae, described by Wilcox in 1941. The genus Heteropogon belongs to the subfamily Brachyrhopalinae, a group of small to medium-sized predatory flies. Members of this genus are known for their characteristic perching behavior on twigs and vegetation while hunting flying insect prey. The specific epithet "arizonensis" indicates the species was described from Arizona, though detailed natural history information for this particular species remains limited.
Heteropogon cazieri
Heteropogon cazieri is a species of robber fly (family Asilidae) described by Wilcox in 1965. It belongs to the subfamily Brachyrhopalinae and is one of approximately 30 described species in the genus Heteropogon. Members of this genus are small to medium-sized predatory flies that perch on vegetation and capture other insects in flight. The species epithet honors entomologist Mont A. Cazier.
Heteropogon chiricahua
A species of robber fly in the family Asilidae, described by Wilcox in 1965. The specific epithet "chiricahua" refers to the Chiricahua Mountains of southeastern Arizona, suggesting a geographic association with this Sky Island region. As with other members of the genus Heteropogon, this species is presumed to be a predatory fly, though specific observations of its behavior and ecology remain undocumented in available sources.
Heteropogon cirrhatus
Heteropogon cirrhatus is a species of robber fly in the family Asilidae, first described by Osten Sacken in 1877. Robber flies in this genus are small to medium-sized predatory insects. The genus Heteropogon is part of the subfamily Brachyrhopalinae. Available information about this specific species is limited.