The phorid fly, Pseudacteon tricuspis Borgmeier, has been released for biological control of red imported fire ant, Solenopis invicta Buren, in many parts of the southern United States. However, little is known about the nutritional ecology and the effects of environmental and physiological factors on lifespan of adult phorid flies under laboratory or field conditions. Here we report the effects of sugar feeding, temperature, gender, mating, and body size on longevity of P. tricuspis. Sugar availability and temperature were the two major factors influencing longevity. In general, sugar feeding increased lifespan by a factor of 2–3. Longevity of P. tricuspis was inversely related to temperature, and the greatest longevity (≈15 d) was recorded for sugar-fed flies kept at 20°C. Longevity declined from ≈15 d at 20°C to 4 d at 33°C for sugar-fed females and from 7 d at 20°C to 2 d at 33°C for sugar-starved females. Similar results were obtained for male P. tricuspis, and gender or mating did not significantly influence longevity. There was no significant difference in longevity between mated and unmated female and male flies, irrespective of diet and temperature. Gender, however, had a significant effect on wing length with females being larger than males. A positive correlation between wing length and longevity was recorded for sugar-starved female and male phorid flies kept at 20°C and for sugar-starved males kept at 28°C, but not for sugar-fed flies or flies exposed to high temperatures. These results suggest that provision of supplemental sugar sources and suitable microclimate near its release sites may enhance the success of P. tricuspis as a biological control agent.