Technical Abstract: Mediterranean fruit fly spatial distribution among different elevations and host plants was determined from a study in Guatemala, where there is an ongoing Sterile Insect Release (SIT) program. Fifty-one pairs of traps (the male-biased Jackson traps, baited with trimedlure, and female-biased cylindrical traps baited with a three component synthetic lure) were placed at predetermined locations along a grid at elevations that ranged from 1017 to 1821 m above sea level. Pairs of traps were placed 25 m apart on suitable host plants, and individual trap locations were recorded using GPS. Numbers of flies captured were recorded weekly for 10 weeks, and captured flies were examined to determine sex and sterility status. On coffee, more flies (sterile, fertile, males or females) were captured at the 1357 elevation than at other elevations considered. On other hosts, captures did not differ among elevations. After the sterile release began, patchy concentrations of fertile (wild) male and female flies were detected. Differences in the distribution of fruit flies may be related to differential mortality due to micro environmental differences in humidity, temperature, and host plant maturity. Implications of these observed distribution patterns require further study