Milichiidae

Myrmecophily has been known in the fly family Milichiidae for more than a hundred years. Most cases involve larvae that live in ant nests (Donisthorpe 1927; Sabrosky 1959; Moser & Neff 1971; Waller 1980), but a group of short-faced Milichia species exhibit myrmecophilous behaviour in the adult stage, mostly in connection with myrmicine ants in the genus Crematogaster. Milichia dectes Collin, 1922, M. proectes Collin, 1922, M. prosaetes Collin, 1922 and probably also M. farquharsoni Collin, 1922 solicit regurgitated food from Crematogaster workers (Farquharson 1919, 1922). In one case involving Milichia dectes, the ant was identified as Crematogaster buchneri. Two species have been observed licking the anal secretions of ants: Milichia myrmecophila de Meijere, 1909, those of Crematogaster difformis, and Milichia brevirostris (de Meijere, 1910), those of Dolichoderus thoracicus (as Dolichoderus bituberculatus).

Wild & Brake (2009) reported on Milichia patrizii Hennig, 1952, a species not previously known to be a myrmecophile, in South Africa. However, the holotype label states that the species is a commensal of Crematogaster, and an unidentified Crematogaster worker specimen (possibly Crematogaster schultzei) is mounted on the same pin as the fly. Milichia patrizii belongs to the myrmecophila species-group within the short-faced group of Milichia species (Brake 1999).

Milichia patrizii next to a Crematogaster tricolor trail on an Acacia branch; (2) A Milichia darts into the middle of the Crematogaster trail to pursue an individual ant. This attempt was unsuccessful, as the ant was able to move past the fly without stopping (Wild & Brake, 2009, Figs 1, 2).
Milichia patrizii pacifies an ant in a successful attack by grabbing the ant’s antennal club between the paired basoflagellomeres of its own antennae; (4) The same attack as pictured in Fig. 3. The ant crouches down while the fly initiates regurgitation process by extending its proboscis into the mouthparts of the ant (Wild & Brake, 2009, Figs 3, 4).
Food exchange between Milichia patrizii and Crematogaster tricolor: (5) General view; (6) An enlargement showing details of the food exchange interaction. The ant’s antenna is enfolded by the pilose clypeal membrane of the fly’s proboscis. The long hairs on the fly’s proboscis likely serve to capture liquids from the mouth of the ant (Wild & Brake, 2009, Figs 5, 6).
Food exchange ends when the fly retracts its mouthparts. The ant briefly sits motionless following the interaction; (8) Trophallaxis food-sharing behaviour between two Crematogaster tricolor nestmates (Wild & Brake, 2009, Figs 7, 8).

A crab spider (top left) has killed a bullet ant queen and at least 2 species of small flies (Milichiidae & Phoridae) have arrived to feed from the carcass and/or lay their eggs. Amazonian Peru. Photo by Alex Wild.

Known Ant Hosts

Ant	Fly Species	Locality	Source	Notes
Atta cephalotes	Milichiella argenteocincta	Argentina, Bahamas, Bolivia, Brazil, Costa Rica, Dominica, Guyana, Panama, Paraguay, Peru, Puerto Rico, Trinidad, Alabama, Florida	Brake, 2009; Milichiidae online
Atta cephalotes	Pholeomyia comans		Moser & Neff, 1971; Milichiidae online
Atta cephalotes	Pholeomyia texensis	Texas	Waller, 1980; Milichiidae online
Atta texana	Pholeomyia comans		Moser & Neff, 1971; Muesebeck, 1980	associated with or potential host
Atta texana	Pholeomyia texensis	Texas	Waller, 1980	associated with or potential host
Azteca constructor	unknown species	Costa Rica	Swann, 2010; Milichiidae online
Azteca trigona	unknown species	Guyana	Swann, 2010; Milichiidae online
Camponotus acvapimensis	Milichia savannaticola		Demming, 1981; Yusah & Fayle, 2014	details of interaction uncertain
Crematogaster buchneri	Milichia dectes		Wild & Brake, 2009
Crematogaster difformis	Milichia myrmecophila		Jacobson, 1910; de Meijere, 1910; Wild & Brake, 2009; Milichiidae online	observed licking the anal secretions of ants
Crematogaster difformis	Milichia savannaticola		Deeming, 1981; Milichiidae online
Crematogaster stollii	Microsimus luteus		Aldrich, 1926; Milichiidae online
Dolichoderus thoracicus	Milichia brevirostris		de Meijere, 1910; Wild & Brake, 2009	observed licking the anal secretions of ants
Formica rufa	Phyllomyza formicae	Denmark, Switzerland, United Kingdom	Donisthorpe, 1927; Hennig, 1937; Hennig, 1952; Milichiidae online
Formica rufa	Phyllomyza securicornis	United Kingdom	Verrall, 1894; Hennig, 1937; Milichiidae online
Harpegnathos saltator	species unknown	India	Peeters et al., 1994; Milichiidae online
Lasius fuliginosus	Milichia ludens	Germany, Norway, United Kingdom	Raddatz, 1873; Okland, 1998; Donisthorpe, 1927; Webb & Ismay, 2003; Poulton, 1919; Milichiidae online
Lasius fuliginosus	Phyllomyza donisthorpei	Sweden, United Kingdom	Donisthorpe, 1927; Andersson, 1971; Milichiidae online
Lasius fuliginosus	Phyllomyza equitans	Finland, Norway, Sweden, United Kingdom	Donisthorpe, 1927; Okland, 1998; Andersson, 1971; Tiensuu, 1946; Donisthorpe, 1927; Duda, 1935; Milichiidae online
Lasius fuliginosus	Phyllomyza flavitarsis	Germany	Raddatz, 1873; Milichiidae online
Lasius fuliginosus	Phyllomyza pallida	Netherlands	de Meijere, 1940; Milichiidae online
Mycetagroicus inflatus	Pholeomyia sp.	Brazil	Wild & Brake, 2009; Jesovnik et al., 2013; Milichiidae online
Polyrhachis illaudata	Milichia sp.	Malaysia	Yusah & Fayle, 2014; Milichiidae online

References