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

The phenology and dispersal abilities of Pseudacteon phorid flies, parasito ids of Solenopsis fire ante, were measured at multiple sites over several y ears. 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. br owni was the most common at all sites and in all years, with a single excep tion. Pseudacteon species were observed hovering over disturbed S, geminata mounds from April through December of most years, although night activity was not observed on days when the air temperature fell below 20 degrees C. Relative abundance patterns varied both temporally and spatially, although a rough positive correlation with rainfall tvas evident at some sites. Over all 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 65 0 m from the nearest S. geminata colony, and appeared to disperse away from host colonies into areas without appropriate hosts in random directions. A lthough populations of host S. geminata in central Texas are fragmented, di stances over which Pseudacteon dispersal frequently occurs may be relativel y large compared with the interpatch distances separating host ant populati ons.