Belongs within: Oestroidea.
The hidden life of a highwayman
Published 17 February 2025
One comment I’ve had cause to make in the past is that it is a shame that blow flies are inherently disgusting because they would otherwise be fascinating. Blow flies and their relatives exhibit a remarkable ecological diversity, pursuing a surprisingly broad range of life styles. Among those which stand out are the highwayman flies of the genus Bengalia.
About eighty species of Bengalia have been described to date from the tropics of Africa and Asia. A single species, B. torosa, has been recorded from northern Australia (Farrow & Dear 1978) though it has been suggested that it may be a recent introduction from Indonesia. Bengalia is currently included in the subfamily Bengaliinae of the blow fly family Calliphoridae though some authors have questioned whether the bengaliines might be better awarded their own family (Rognes 2011). In contrast to the iridescent coloration of other blow flies, Bengalia species are typically yellow or brown. Other distinctive features include an antero-posteriorly compressed head, a ventrally projecting clypeus and stout mouthparts (Rognes 2005).
Whereas other blow flies are commonly scavengers on decaying plant or animal matter, Bengalia species are predators. Targeted prey include termites emerging from broken nests and foraging tunnels. They are also known to linger near ant trails and seize pupae and larvae being transported by the ants. These prizes are then carried a short distance away to a safe spot where they may be sucked dry. It is this thieving behaviour that has led some authors to label Bengalia species ‘highwayman flies’.
The larval habits of Bengalia species, in contrast, are all but unknown. Larvae were only described for the first time by Szpila et al. (2016) from eggs laid in the lab. The larvae possessed strong mouth-hooks that differed from those found in carrion-feeding fly larvae. Features of the cuticle might potentially be related to burrowing in soil. Oviposition has not been definitively observed in the wild though at least one observation has been made of a female digging into soil excavated by alate termites (Rognes 2011). It seems most likely that Bengalia larvae feed in the nests of termites, though whether they feed on dead termites and other debris, or on the fungi that grow in many termite nests, remains to be discovered.
Systematics of Bengalia
<==Bengalia Robineau-Desvoidy 1830 [Bengaliinae, Bengaliini]PG-M04
| i. s.: B. peuhiKP10
|--*B. (Bengalia) labiata Robineau-Desvoidy 1830PG-M04
|--B. (Eubengalia Townsend 1926)F92
| |--B. (*E.) depressa Walker 1858PG-M04
| |--B. (E.) emarginata Malloch 1927F92
| |--B. (E.) latro de Meij. 1910 [incl. B. bezzii Senior-White 1923]F92
| `--B. (E.) varicolor (Fab. 1805) [=Musca varicolor]F92
`--B. (Ochromyia Macquart 1835)F92, PG-M04 (see below for synonymy)
|--‘Musca’ jejuna Fabricius 1787 (see below for synonymy)PG-M04
|--B. (O.) chekiangensis Fan 1965F92
|--B. (O.) escheri Bezzi 1913F92
|--B. (O.) taiwanensis Fan 1965F92
`--B. (‘Anisomyia’) torosa (Wiedemann 1819)F92 (see below for synonymy)
Bengalia (‘Anisomyia’) torosa (Wiedemann 1819)F92 [=Musca torosaPG-M04; incl. M. jejuna Roubaud 1911 non Fabricius 1786PG-M04, Bengalia (*Parabengalia) jejunaPG-M04, Anisomyia lateralis Macq. 1843F92]
Bengalia (Ochromyia Macquart 1835)F92, PG-M04 [incl. Anisomyia Walker 1860PG-M04, Homodexia Bigot 1885PG-M04, Parabengalia Roubaud 1911PG-M04]
‘Musca’ jejuna Fabricius 1787 [=*Ochromyia jejuna; incl. M. favillacea Walker 1860, M. (*Anisomyia) favillacea, *Homodexia obscuripennis Bigot 1885]PG-M04
*Type species of generic name indicated
References
[F92] Fan Z. 1992. Key to the Common Flies of China 2nd ed. Science Press: Beijing.
Farrow, R. A., & J. P. Dear. 1978. The discovery of the genus Bengalia Robineau-Desvoidy (Diptera: Calliphoridae) in Australia. Journal of the Australian Entomological Society 17: 234.
[KP10] Kutty, S. N., T. Pape, B. M. Wiegmann & R. Meier. 2010. Molecular phylogeny of the Calyptratae (Diptera: Cyclorrhapha) with an emphasis on the superfamily Oestroidea and the position of Mystacinobiidae and McAlpine’s fly. Systematic Entomology 35: 614–635.
[PG-M04] Peris, S. V., & D. González-Mora. 2004. Clave de identificación para los géneros de Calliphoridae del mundo. Subfamilias con vena remigium desnuda y creación de una nueva subfamilia. Bol. R. Soc. Esp. Hist. Nat. (Sec. Biol.) 99 (1–4): 115–144.
Rognes, K. 2005. Bengalomania—a review of Andy Z. Lehrer’s book on Bengalia Robineau-Desvoidy, 1830 and related works (Diptera, Calliphoridae). Studia Dipterologica 12 (2): 443–471.
Rognes, K. 2011. A review of the monophyly and composition of the Bengaliinae with the description of a new genus and species, and new evidence for the presence of Melanomyinae in the Afrotropical region (Diptera, Calliphoridae). Zootaxa 2964: 1–60.
Szpila, K., S. K. Sinha & T. Pape. 2016. First documentation of early preimaginal stages of the blowfly Bengalia (Diptera: Calliphoridae). Zoologischer Anzeiger 263: 16–23.