These bee-mimics are superficially similar to Laphria – both are very hairy with yellow and black hairs. A lot of early research was put into determining if these “bee killers” were a threat to apiaries, which is doubtful. Bromley (1946) found that 83% of Mallophora orcina‘s and 79% of M. bomboides‘s diet is composed of honey bees. They are opportunistic hunters, and that study may have been looking near apiaries. Fattig (1933) found they took honey bees, bumblebees, and yellow jackets most often.
Mallophora are thought to mimic bumblebees. Bumblebees produce a conspicuous buzzing noise as a warning signal to potential predators, and some bumblebee mimics have taken advantage of it, producing a similar noise (Brower, et al., 1960; Hull, 1962).
In one of the few studies of mimicry in Asilidae, Brower et al. (1960) devised an experiment comparing the palatability of the asilid fly, Mallophora bomboides, and its model, Bombus americanus. When bees, the asilid flies, and edible dragonflies were presented to toads in a controlled experiment, toads learned to reject both the bees and the asilid flies. Control toads that were not given the inedible bees did not reject the mimic asilid flies. For one of the toads, an asilid fly bit the toad on the nose during the first trial. After the bite, this particular toad refused either the mimic asilid flies or the bees, but not the edible dragonflies.
Chris Cohen created this key to the North American species and UF/IFAS has this key for Florida. The tropical species of Mallophora are often less hairy and look different than the North American species.
Mallophora orcina, Southern Bee-Killer
Mallophora orcina and M. bomboides are almost entirely temporally segregated in Florida, with M. orcina in early summer, and M. bomboides in later summer and fall. There are exceptions, but the hairs are typically yellow in M. oricina and white in M. bomboides. The tip of the abdomen is black. Hairs under abdomen are black. Males have white tuft of hair on underside of hind tibia.
Size: 14-20 mm
FL Season: April to August, though mostly May and June.
FL Range: Throughout. There are museum records for Dade and Monroe Counties, though they may be in error. Modern records only show it south to Sarasota, Highlands, and Palm Beach Counties.
Mallophora bomboides, Florida Bee-Killer
Typically has whitish hairs. The tip of the abdomen has white/yellow hairs. Also note the pale hairs on the rear legs, often with longer hairs at the apex of the tibia on males, like ankle pom-poms. The hairs under the abdomen are also white.
Size: 23-30 mm
FL Season: Late June to December, though mostly August to November.
FL Range: Predominantly the peninsula, though there are two records from near Tallahassee.
Mallophora atra, Black Bee-Killer
Black scutum (top disc of thorax), abdomen typically black, yellow/white hairs on mystax, beard, and around eyes. Males of this species also have the white ankle pom-poms like M. bomboides. The habitat, range, and seasonality of M. atra are almost identical to M. bomboides, and I suspect it may simply be a rare black-haired form of M. bomboides. Cole & Pritchard (1964) had the same thought, noting that M. atra and M. bomboides were structurally identical.
Size: 23-26 mm
FL Season: August to November. There is one May record.
FL Range: Peninsula, from Gainesville south.
Known from Paraguay. Artigas & Angulo include a record from “Florida,” but Artigas & Papavero (1997) indicate that record is “highly doubtful.”
Artigas & Angulo (1980) describe M. thompsoni as: “Posterior tibiae in lateral view, with hairs that increase in length toward the basal third; hairs of the basal half are all white and the rest are dark-greyish. Head with abundant yellowish white hairs. Abdomen with sparse white hair only, mid-tibiae and hind femora with black hair; hind tarsi with dark-greyish hair, dorsum of each tarsomere with white erect hair”
Artigas, J. N. & A. O. Angulo. (1980). Revision del gênero Mallophora Macquart por sistemática alfa y taxonomia Numérica (Diptera-Asilidae). Gayana, Zool. 43:1-182, 176 figs.
Artigas, J. N. & Papavero, N. (1997). The American genera of Asilidae (Diptera): Keys for identification with an atlas of female spermathecae and other morphological details. IX.6. Subfamily Asilinae Leach – Mallophora – group, with a catalogue of the Neotropical species. Arquivos de Zoologia do Estado de Sao Paulo 34(4): 97-120; Sao Paulo.
Bromley, S. W. (1925). The Bremus Resembling Mallophorae of the Southeastern United States. Psyche, 32(3), 190-194.
Bromley, S. W. (1946). Bee-killing Asilidae of the southeastern states (Diptera). Proceedings of the Entomological Society of Washington, 48, 16-17.
Bromley, S. W. (1950). Florida Asilidae (Diptera) with description of one new species. Annals of the Entomological Society of America, 43(2), 227-239.
Brower, L. P., Brower, J. V. Z., & Westcott, P. W. (1960). Experimental studies of mimicry. 5. The reactions of toads (Bufo terrestris) to bumblebees (Bombus americanorum) and their robberfly mimics (Mallophora bomboides), with a discussion of aggressive mimicry. The American Naturalist, 94(878), 343-355.
Cole, F. R., & Pritchard, A. E. (1964). The Genus Mallophora and Related Asilid Genera in North America: (Diptera: Asilidae). University of California Press.
Coquillett, D. W. (1893). Synopsis of the asilid genera Mallophora and Nicocles. The Canadian Entomologist, 25(5), 118-120.
Fattig, P. W. (1933). Food of the robber fly, Mallophora orcina (Wied)(Diptera). The Canadian Entomologist, 65(5), 119-120.
Hull, F. M. (1962). Robber flies of the world. 907 pp. Washington. Bulletin of the United States National Museum, 224.
Steck, G. J. (2005). Bee Killers, Mallophora bomboides (Wiedemann), Mallophora orcina (Wiedemann), and Mallophora nigra Williston (Insecta: Diptera: Asilidae): EENY-315/IN591, 3/2004. EDIS, 2005(3).