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Home » Guide » Arthropods (Arthropoda) » Hexapods (Hexapoda) » Insects (Insecta) » Flies (Diptera) » Orthorrhapha » Asiloidea » Robber Flies (Asilidae) » Asilinae » Hammertails (Efferia) » Nerax group (Efferia Nerax group) » Eastern Hammertail (Efferia aestuans)

Species Efferia aestuans - Eastern Hammertail

Classification · Synonyms and other taxonomic changes · Explanation of Names · Size · Identification · Range · Remarks · See Also · Internet References · Works Cited
Mating Robberflies with prey! - Efferia aestuans - male - female Robber Fly ID Request - Efferia aestuans Robberfly - Efferia aestuans - female Robberfly - Efferia aestuans Efferia aestuans - male Robber fly - Efferia aestuans - female Efferia aestuans Black Mustache Robber Fly - Lateral - Efferia aestuans - male
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon (Orthorrhapha)
Superfamily Asiloidea
Family Asilidae (Robber Flies)
Subfamily Asilinae
Genus Efferia (Hammertails)
No Taxon (Nerax group)
Species aestuans (Eastern Hammertail)
Synonyms and other taxonomic changes
Nerax aestuans
Explanation of Names
Efferia aestuans (Linnaeus 1763)
aestuans = 'scolding, boiling'

Eastern Hammertail: https://www.robberfliesoftheworld.com/NA_CommonNames.php
Size
male 19 mm, female 21 mm (1)
Identification
tibiae partially reddish, mystax black, ventral surface of abdomen has long white hairs; female has long blade-like ovipositor

Efferia kondratieffi Bullington and Lavinge (1984) is very similar. Robberfly.org says:
" E. aestuans are longer overall. Compared to E. aestuans, males have a shorter epandrium with a different shape to the tip of the epandrium. Females have a shorter ovipositor (3-4 mm) than E. aestuans (5-7 mm) giving it a more stout appearance, and a shoter arista (tip of antennae) (0.6-0.85 mm in E. kondratieffi vs. 0.7-1.2 mm in E. aestuans)."
Bullington and Lavigne (1984) also identify a possible additional species (Tex-coastalis) from Oklahoma and Texas. Current (2024) status of this taxon is unclear.
Reference: Bullington and Lavigne (1984). Description and Habitat of Efferia kondratieffi sp. nov. with Notes on Efferia aestuans (L.) (Diptera: Asilidae). Annals of the Entomological Society of America 77(4):404-413. DOI:10.1093/aesa/77.4.404 (Research Gate link)
Range
NH-ON-FL to ND-WY-UT-NM(2)
Remarks
The most likely robber fly to land on humans. (comment by Herschel Raney)
Sometimes fearless. The males are much less common and harder to approach. (comment by Herschel Raney)
The commonest species of Asilinae in the northeast (comment by Herschel Raney)
The type species of Efferia
See Also
E. albibarbis has white mystax, and shorter, more cone-like ovipositor
Efferia kondratieffi (see Remarks here)
Internet References
Species profile (3)
Robberfly.org
Works Cited
1.Efferia Coquillett in America North of Mexico
Wilcox, J. 1966. Proceedings of the California Academy of Sciences, 4th series., 34:85-234.
2.Information on robber flies, compiled by F. Geller-Grimm
3.Lavers N. (2007) The robber flies of Crowley's Ridge, Arkansas: An illustrated field guide
Contributed by john and jane balaban on 14 June, 2005 - 5:36pm
Additional contributions by cotinis, Robin McLeod, v belov, Chris Cohen
Last updated 5 June, 2024 - 8:58pm

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