Fire-ant
Guides
Caenocholax fenyesi
Caenocholax fenyesi is a strepsipteran parasitoid in the family Myrmecolacidae, notable for extreme sexual dimorphism and heterotrophic heteronomy—males and females occupy different hosts throughout their life cycles. Females are endoparasites of Orthoptera, while males parasitize ant larvae and pupae, primarily Solenopsis invicta (red imported fire ant) in the United States and related native fire ants in Mexico, Central America, and parts of South America. The species has a sporadic distribution across the southern United States, Central America, and South America, with three recognized cryptic subspecies that are morphologically similar but genetically distinct. Adult males are free-living with a lifespan of only hours to a few days, severely constraining dispersal and contributing to genetic bottlenecking effects.
Pseudacteon
Ant-Decapitating Flies
Pseudacteon is a genus of phorid flies comprising over 70 described species, commonly known as ant-decapitating flies. These parasitoids are specialized on ants, particularly Solenopsis fire ants, with females injecting eggs directly into host workers. The larval development occurs entirely within the ant's head capsule, culminating in decapitation and pupation inside the detached head. Several species have been introduced to the United States as biological control agents against invasive red imported fire ants.
Pseudacteon curvatus
fire ant decapitating fly, little decapitating fly
Pseudacteon curvatus is a small phorid fly parasitoid known as the 'little decapitating fly' due to its life cycle in which mature larvae cause decapitation of host fire ants upon emergence. Native to South America, it has been introduced to the United States as a classical biological control agent against invasive imported fire ants (Solenopsis invicta and S. richteri). The species exhibits host specificity toward Solenopsis fire ants and has been the subject of extensive research on laboratory rearing methods, host preference behavior, and field establishment following releases.
Pseudacteon tricuspis
fire ant decapitating fly, phorid fly
Pseudacteon tricuspis is a parasitoid phorid fly that specifically targets the red imported fire ant (Solenopsis invicta). Adult females deposit eggs directly into worker ants, and the developing larvae eventually decapitate the host. The species was introduced to the United States in the late 1990s as a biological control agent against this invasive ant. Native to South America, it has now established populations across the southeastern United States.
Solenopsis geminata
tropical fire ant, Geminata-group fire ant
Solenopsis geminata, the tropical fire ant, is a native New World species with a broad distribution spanning the southern United States through Central and South America, and introduced populations across Asia, the Pacific Islands, and Africa. The species exhibits a foraging strategy tradeoff between discovery efficiency and competitive territorial dominance compared to its congener S. xyloni, with S. geminata being less efficient at resource discovery but superior in competitive encounters. Invasive populations demonstrate adaptive strategies to overcome inbreeding costs, including pleometrosis (cooperative colony founding by multiple queens) and execution of diploid male larvae. The species serves as host to Pseudacteon phorid fly parasitoids.
Solenopsis richteri
Black Imported Fire Ant, BIFA
Solenopsis richteri, the black imported fire ant, is a South American native fire ant species that has been introduced to North America. Once considered a subspecies or color variant of Solenopsis invicta, it is now recognized as a distinct species with demonstrably different range and ecological preferences. It appears more cold-tolerant and less dominant than the red imported fire ant. In its native Argentina, it is attacked by six species of Pseudacteon phorid flies that significantly reduce its foraging activity. The species hybridizes with S. invicta where their ranges overlap, particularly in Tennessee. In Eritrea, it has been documented as a serious agricultural pest of crops and grazing areas.