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Family Asilidae - Robber Flies

spider killer - Tipulogaster glabrata Robber Fly, with prey - Diogmites discolor Robber Fly - Laphria posticata Wasp mimic Robber Fly - Ceraturgus fasciatus Three-banded Robber Fly - Stichopogon trifasciatus Fly Spp. - Holcocephala Promachus rufipes - male Friendly Robber - Efferia aestuans - male Killer with food - Mallophora orcina Robber Fly - Efferia albibarbis - 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)
Other Common Names
Assassin Flies (1)
Pronunciation
ah-SILL-li-dee
Synonyms and other taxonomic changes
higher taxa recently redefined -- see a summary at(2)
Explanation of Names
see Asilus
Numbers
~1,040 spp. in ~100 genera in our area, >7,000 described species in 530 genera worldwide(3); ~200 spp. in Canada
Overview of our fauna (* –taxa not yet in the guide; classification adapted from(4) –see note):
Family Asilidae
Size
5-30 mm, possibly larger (typically 9-15 mm)
Identification
Medium-sized to large predatory flies, often perch in exposed location and make short flies after prey. Typical family characteristics:
top of head depressed between eyes, with three ocelli in the depression
body from very hairy to nearly bare
body typically elongated, with tapered abdomen
some are bee/wasp mimics
face usually "bearded", with prominent mystax
mouthparts modified to inject prey with saliva, similar in both sexes (unlike in blood-sucking flies, such as Tabanidae)
antennae three-segmented, third segment elongate and often with terminal style
Pupa:
Range
worldwide
Habitat
most diverse in dry, open habitats; larvae usually in soil or decaying wood
Season
Typically summer
Food
Predatory on a variety of other insects.
Life Cycle
Adults lay eggs in the soil or in plants. A few, such as Mallophora and Megaphorus form an egg mass on a plant stem (see photo here). Larvae often predatory, consuming eggs and larvae of other insects in decaying matter. Typically overwinter as pupa, emerge in spring. Life cycle is 1-3 years.
Remarks
CAUTION! Large robber flies may bite if mishandled (forum discussion here)
Genera not yet in the guide [per(3)]:
Beameromyia 15 spp., mostly sw. (5 in se. US)
Bohartia 6 spp., w./sw. US
Apachekolos 4 sw. spp. + 1 sp. in se.
Omninablautus 4 spp. w./sw.
Hadrokolos 3 spp. OK-TX-NM
Itolia 3 spp. AZ-NV-CA
Nannodioctria 2 spp. FL CA
Prolatiforceps 2 spp. NM-AZ
The following are represented by a single species each:
northern transcontinental: Rhadiurgus
FL TX: Leptopteromyia
w. NA: Stilpnogaster, Willistonina
sw. US: Atomosiella
TX: Amblyonychus
NM-AZ: Atoniomyia
AZ: Bromleyus, Dicranus, Orrhodops, Perasis
TX-NM: Plesiomma
CA: Dasypogon
This is a fairly contentious issue. Until recently, most workers have favored a version of the Papavero classification (1973-2009; see recent updates in the Catalogue of Neotropical Diptera or the Manual of Neotropical Diptera, both 2009). I used this same classification in my unpublished checklist of Nearctic Asilidae(4) (used by Herschel Rainey for his state lists). In 2009, things were changed significantly by Torsten Dikow(6)(7) with publication of his PhD work. His morphology-only analysis of 158 spp. yielded 720 most parsimonius cladograms, the favored classification selected being one comprised of 14 subfamilies. A combined total evidence analysis was then performed, adding DNA sequencing data from 77 of the original 158 spp. studied (representing 12 of the 14 subfamilies sampled morphologically). Results from the combined total evidence analysis failed to support the morphology-only classification in many instances, with about half of the subfamilies appearing in multiple positions (=nonmonophyletic) in the favored combined cladograms. Another problem is that some of the subfamilies recognized lack external characters useful for dichotomous keys or gestalt recognition: many features used in the morphology data matrix require extensive dissection, and those in the total evidence analysis are partly molecular. Ironically, the only truly congruent classification resulting from both methodologies is one where only three subfamilies are recognized (Asilinae, Laphriinae, Dasypogoninae), like the pioneering classifications of Macquart and Loew in the early 1800s! Dikow's work has demonstrated that some of the modern subfamilies and tribes (those more recent than the classic ones just mentioned) are not monophyletic, but problems are apparent with his new classifications as well. More species need to be sampled for phylogenetic study – especially those with DNA sequencing data – even though total evidence analysis has so far yielded conflicting results. Until a stable, practical classification is available, some version of the Papavero classification is probably still preferable, and I recommend using the eight subfamilies from(3) (currently used on BG) with no tribes recognized (some tribes are apparently monophyletic but others are not, and details and relationships are controversial).
See Also
Print References
Dennis D.S., Barnes J.K. (2011) Tentative key to robber fly (Diptera: Asilidae) subfamilies based on pupal cases. Zootaxa 3031: 37–46 (Full text)
Hull F.M. (1962) Robber flies of the world: the genera of the family Asilidae, U.S. Nat. Mus. Bull. 224: 1-907 (Full text: pp. 1-427 | 428-907)
(8)
Internet References
(9)(10)(11)(12)(13)(14)