Phenology and dispersal in Pseudacteon flies (Diptera: Phoridae), parasitoids of Solenopsis fire ants (Hymenoptera: Formicidae)


The phenology and dispersal abilities of Pseudacteon phorid flies, parasitoids of Solenopsis fire ants, were measured at multiple sites over several years. Four Pseudacteon species [P. browni Disney, P. spatulatus (Malloch), P. crawfordi Coquillett, and an undescribed species, P. sp. A.] were found in the vicinity of 5 S. geminata (F.) populations over a 3-yr period. P. browni was the most common at all sites and in all years, with a single exception. Pseudacteon species were observed hovering over disturbed S. geminata mounds from April through December of most years, although flight activity was not observed on days when the air temperature fell below 20°C. Relative abundance patterns varied both temporally and spatially, although a rough positive correlation with rainfall was evident at some sites. Overall sex ratios were always highly male-biased at all sites and in all years, with 1 exception. Pseudacteon phorids were found at distances of up to 650 m from the nearest S. geminata colony, and appeared to disperse away from host colonies into areas without appropriate hosts in random directions. Although populations of host S. geminata in central Texas are fragmented, distances over which Pseudacteon dispersal frequently occurs may be relatively large compared with the interpatch distances separating host ant populations.

Document Type





Biological control, Dispersal, Parasitism, Phenology, Pseudacteon, Solenopsis

Publication Date


Journal Title

Annals of the Entomological Society of America