workers and 2 g of brood. As described above, the five trays of S. gentinata were set out

first for 30 min. Solenopsis gentinata trays were then removed and replaced with the S.

invicta trays and these trays were observed for 30 min. At the conclusion of 30 min, the

five trays ofS. invicta were replaced again with the five trays ofS. gentinata for an

additional 30 min. Attacking flies were collected at 5 min intervals as described above.

These methods were replicated on two days (five days apart) at the same site mentioned

above.

 Results

 The P. curvatus flies were not attracted to any of the 15 non-Solenopsis genera

during the sequential series trials over the two days (Table 4-1). However, the flies were

readily attracted to S. invicta (99 on day 1 and 38 on day 2, Table 4-1). As is normal,

these flies hovered above their host, oriented themselves to workers, and readily struck

the thorax of workers during oviposition. When the six S. invicta trays were removed and

replaced again with the 15 trays of non-Solenopsis ants, P. curvatus flies were not

observed hovering over any of the non-Solenopsis trays. Pseudacteon~ddd~~~ddd~~~dd curvatus flies were

present at all six S. invicta trays during the trials.

 In the S. invicta versus S. gentinata trials, P. curvatus flies were not observed

hovering or attacking over S. gentinata during the first day and only 2-4 flies were

observed hovering on the second day (Table 4-1). Flies collected above the native fire

ants generally hovered briefly without attacking. Only one fly attempted to oviposit, but

it flew away immediately after without returning. In quarantine tests, this biotype would

occasionally attack S. gentinata workers but attacks were never successful (Vazquez et al.

2004). Pseudacteon curvatus flies were present at all five S. invicta trays during the first

day and present at four of five trays on the second day. Pseudacteon curvatus flies were