1.) Sentinel traps were used to survey for parasitoids of frugivorous drosophilids in Virginia fruit cropping systems, and determine if parasitoids were attacking invasive flies Drosophila suzukii (Matsumura) and Zaprionus indianus Gupta (Diptera: Drosophilidae) in the field. Two parasitoids of frugivorous drosophilids, Leptopilina boulardi (Barbotin, Carton, and Kelner-Pillault) (Hymenoptera: Figitidae) and Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae), were reared, but only one P. vindemiae was reared from D. suzukii, and no parasitoids were reared from Z. indianus. Most parasitoids were reared from alternate host Drosophila melanogaster Meigen and other wild drosophilids. 2.) The ability of these parasitoids to attack D. melanogaster, D. suzukii and Z. indianus under controlled conditions was tested. Larval parasitoid L. boulardi did not develop on D. suzukii or Z. indianus, just D. melanogaster. Pupal parasitoid P. vindemiae successfully developed on all three fly species, but also increased pupal fly mortality. 3.) Olfactometry was used to ascertain if L. boulardi and P. vindemiae are selective about the type of fruit their hosts feed in. Results showed that among cherry, raspberry, blueberry, grape, and banana, L. boulardi preferred raspberry and banana to cherry, and preferred grape least, but no fruit was most preferred. Insufficient data were obtained for P. vindemiae. We conclude that parasitoids of Virginia are unlikely to provide effective biological control for D. suzukii or Z. indianus, and classical biological control should be investigated as a pest management option. Olfactometry results indicate tritrophic selectivity by Drosophila parasitoids, suggesting multiple parasitoids could be required for effective biological control. / Master of Science in Life Sciences / The spotted wing drosophila (henceforth SWD) is a globally invasive vinegar fly originating from southeast Asia, and is economically damaging to producers of small fruit, such as berries, cherries, and grapes. The African fig fly (henceforth AFF), a relative of SWD, is another recently invasive species to North America (originating from Africa) that often occurs simultaneously with SWD infestations, but its economic threat to North America is still unclear. With the economic threat posed by SWD, and potential threat posed by AFF, it is important to understand their relationships with other organisms in their environment, especially natural enemies, such as parasitoid wasps. Such information is integral for researchers to develop effective control methods, and will help determine if natural enemies can be used to our advantage as biological control agents. Biological control also helps to limit the use of chemical insecticides, mitigating the development of insecticide resistance in the pests. This project employed unique field trapping methods and laboratory bioassays to investigate the relationships of SWD and AFF with parasitoid wasps in affected fruit cropping systems in southwestern Virginia. We discovered that parasitoids of vinegar flies are present in Virginia fruit cropping systems, but they do not help to control populations of SWD and AFF. The parasitoids that are present prefer to attack other fly species, are unable to attack SWD and AFF, or do not attack in high enough numbers to have an impact on SWD or AFF populations. Biological control success is more likely to come from parasitoid species that have co-evolved with SWD and AFF in their native ranges.