A view from above of a female Efferia deserti - note the converging veins R4 and R5 at the wing tip and the narrow cell r4 between both veins; quite a few Efferia species (like this one) have a short vein stub branching off near the split of R4 from R5Male of Efferia aestuansFemale of Efferia aestuans
Small to large-sized robber flies (10–40 mm) with distinctly different shape of the posterior end of the
abdomen in males versus females. Females have a short or long
ovipositor that is hairless and short conical to slender wedge-shaped, its color is usually glossy black. Males have a "helicopter tail" with glossy black
claspers that are covered in hairs, forming part of a complex genital structure (the combined
epandrium and hypandrium) that is clearly larger than the abdominal segments and is oriented diagonally to vertically upwards relative to the main body axis.
Abdominal coloration is usually greyish to brownish in females, versus more contrasting with silvery and/or black segments or patches in males. In both sexes the tip of the genitalia usually extends past the wing tips. Wings are clear or uniformly tinted, with tints varying from transparent brown to dark black.
Venation includes a recurrent vein on
R1, narrow cell r4,
R4 extending roughly parallel to
R5 or converging moderately with R5 towards the wing tip.
Biology
As is typical for robber flies, adult Efferia are ambush predators, taking off from a resting position on the ground or on a branch to intercept other flying insects in mid-air. Prey are taken from a wide variety of insect orders: Robert Lavigne's Predator-Prey Database for the family Asilidae[1] has 918 records for Efferia species feeding frequently on
Diptera,
Homoptera,
Hymenoptera,
Heteroptera,
Coleoptera,
Lepidoptera,
Orthoptera, as well as a few reports of prey species belonging to
Neuroptera,
Odonata,
Ephemeroptera - and even one record for
Araneae (spiders). Other asilids are frequently preyed upon, and
cannibalism is common as well.
Efferia species of
deserts and
grasslands can occur in high abundance, at times even exceeding one individual per square foot. They tend to perch close to the ground and often remain quite immobile - sometimes until they are about to get stepped on. Spotting them is often a matter of first hearing the typically short evasive flight, before seeing where one landed. This is especially true for the males, which emit a characteristic pulsing buzz during the few seconds in flight; this sound tends to be loud and noticeably higher pitched than that of a flying female.[2]
Taxonomy
This is an as yet provisional list of 241 recognized
species, combined from 235 entries for accepted species of Efferia in GBIF[3] plus 6 species only listed as valid in other recent sources[4][5][6]
Efferia female feeding on a beefly (probably Villa agrippina)Efferia female using its wedge-shaped ovipositor to lay eggs inside a shriveled flower calyx
Combined analysis of morphological and molecular characters places Efferia pogonias in a clade corresponding to the subfamily
Asilinae, usually with Proctacanthus philadelphicus as sister taxon and always resolving this subfamily as monophyletic.[9]
^Cannings, Robert A. (2011). "Efferia okanagana, a new species of robber fly (Diptera: Asilidae) from the grasslands of southern British Columbia, Canada, with notes on taxonomy, biology, distribution, and conservation status". The Canadian Entomologist. 143 (6): 578–93.
doi:
10.4039/n11-032.
S2CID86363504.
^Scarbrough, Aubrey G.; Stevens, Lawrence E.; Nelson, C. Riley (2012). "The albibarbis-complex of Efferia Coquillett, 1910 from the Grand Canyon region, southwestern U.S.A., with three new species and new distribution records (Diptera: Asilidae)". The Pan-Pacific Entomologist. 88: 58–86.
doi:
10.3956/2012-07.1.
S2CID85852535.
A view from above of a female Efferia deserti - note the converging veins R4 and R5 at the wing tip and the narrow cell r4 between both veins; quite a few Efferia species (like this one) have a short vein stub branching off near the split of R4 from R5Male of Efferia aestuansFemale of Efferia aestuans
Small to large-sized robber flies (10–40 mm) with distinctly different shape of the posterior end of the
abdomen in males versus females. Females have a short or long
ovipositor that is hairless and short conical to slender wedge-shaped, its color is usually glossy black. Males have a "helicopter tail" with glossy black
claspers that are covered in hairs, forming part of a complex genital structure (the combined
epandrium and hypandrium) that is clearly larger than the abdominal segments and is oriented diagonally to vertically upwards relative to the main body axis.
Abdominal coloration is usually greyish to brownish in females, versus more contrasting with silvery and/or black segments or patches in males. In both sexes the tip of the genitalia usually extends past the wing tips. Wings are clear or uniformly tinted, with tints varying from transparent brown to dark black.
Venation includes a recurrent vein on
R1, narrow cell r4,
R4 extending roughly parallel to
R5 or converging moderately with R5 towards the wing tip.
Biology
As is typical for robber flies, adult Efferia are ambush predators, taking off from a resting position on the ground or on a branch to intercept other flying insects in mid-air. Prey are taken from a wide variety of insect orders: Robert Lavigne's Predator-Prey Database for the family Asilidae[1] has 918 records for Efferia species feeding frequently on
Diptera,
Homoptera,
Hymenoptera,
Heteroptera,
Coleoptera,
Lepidoptera,
Orthoptera, as well as a few reports of prey species belonging to
Neuroptera,
Odonata,
Ephemeroptera - and even one record for
Araneae (spiders). Other asilids are frequently preyed upon, and
cannibalism is common as well.
Efferia species of
deserts and
grasslands can occur in high abundance, at times even exceeding one individual per square foot. They tend to perch close to the ground and often remain quite immobile - sometimes until they are about to get stepped on. Spotting them is often a matter of first hearing the typically short evasive flight, before seeing where one landed. This is especially true for the males, which emit a characteristic pulsing buzz during the few seconds in flight; this sound tends to be loud and noticeably higher pitched than that of a flying female.[2]
Taxonomy
This is an as yet provisional list of 241 recognized
species, combined from 235 entries for accepted species of Efferia in GBIF[3] plus 6 species only listed as valid in other recent sources[4][5][6]
Efferia female feeding on a beefly (probably Villa agrippina)Efferia female using its wedge-shaped ovipositor to lay eggs inside a shriveled flower calyx
Combined analysis of morphological and molecular characters places Efferia pogonias in a clade corresponding to the subfamily
Asilinae, usually with Proctacanthus philadelphicus as sister taxon and always resolving this subfamily as monophyletic.[9]
^Cannings, Robert A. (2011). "Efferia okanagana, a new species of robber fly (Diptera: Asilidae) from the grasslands of southern British Columbia, Canada, with notes on taxonomy, biology, distribution, and conservation status". The Canadian Entomologist. 143 (6): 578–93.
doi:
10.4039/n11-032.
S2CID86363504.
^Scarbrough, Aubrey G.; Stevens, Lawrence E.; Nelson, C. Riley (2012). "The albibarbis-complex of Efferia Coquillett, 1910 from the Grand Canyon region, southwestern U.S.A., with three new species and new distribution records (Diptera: Asilidae)". The Pan-Pacific Entomologist. 88: 58–86.
doi:
10.3956/2012-07.1.
S2CID85852535.