In recent years, research efforts on controlling imported fire ants have focused on

natural enemies such as the parasitic ant Solenopsis daguerrei (Santschi) (Calcaterra et al.

1999, 2000, Briano et. al. 2002), the microsporidium pathogen Jhelohania solenopsae

Knell, Allen & Hazard (Oi et al. 2001, Oi and Williams 2002), and dipteran parasitoids in

the genus Pseudacteon~ddd~~~ddd~~~dd Coquillett (Feener 2000, Porter 1998a, Morrison 2000). Earlier

work noted that Pseudacteon species that attack fire ants appear to be specific to fire ants

(Borgmeier and Prado 1975; Disney 1994). Field tests in both South America (Porter et

al. 1995) and in the United States (Vazquez and Porter 2004) along with laboratory tests

in South America (Folgarait et al. 2002) and the United States (Gilbert and Morrison

1997, Porter and Alonso 1999, Porter 2000, Vazquez et al. 2004a) have demonstrated

Pseudacteon species to be host specific to Solenopsis fire ants.

 The small decapitating fly, Pseudacteon curvatus Borgmeier, normally parasitizes

fire ant workers in the saevissima complex in South America (Borgmeier 1925, Porter

1998a). Pseudacteon curvatus is distributed over a large geographical area from Sho

Paulo, Brazil to Buenos Aires province, Argentina (Folgarait et al. 2004, Porter and

Pesquero 2001). Phorid flies have a unique characteristic of decapitating their host during

pupation and affecting fire ant behaviour during oviposition attempts (Morrison 1999).

The life cycle of a Pseudacteon fly begins with a torpedo-shaped egg oviposited into the

thorax of a worker ant (Porter 1998a). The egg dramatically increases in size and

completes development in about 4 days (Consoli et al. 2001). The first instar spends a

short time (about a day) in the thorax and molts into the second instar before it moves

into the ant' s head (Consoli et al. 2001). During most of the third instar, the maggot

probably relies on ant hemolymph for nutrition before pupation (Porter 1998a).