Anastrepha spp. (Diptera: Tephritidae) larval behavior on the ground was quantified, and biotic and abiotic mortality factors were identified from the moment larvae exit fruit until they secure pupation sites in the soil in four environments that differed in climate, soil structure, and fruit tree composition in tropical Mexico (State of Veracruz). Distribution of pupae was influenced by fruit position on the ground but not by shade, litter depth, average soil temperature, soil pH, vegetation cover, and number of predacious insects per surface unit. At all sites, most larvae (90%) entered the soil after exiting the fruit within 10 min, but only at one site did larvae die because of sun exposure during the hottest part of the day. The most important biotic mortality factor at all sites was predation by ants, which in turn was influenced by temperature, humidity, and soil dampness, and varied significantly among host trees within a site. Ants commonly attacked larvae within 5 min of exit from fruit at all but one site. In laboratory experiments, larvae exposed to ant attack pupated at greater depths than larvae exposed to ants but that were not attacked (which in turn pupated at greater depths than larvae not exposed to ants).