Abstract An introduced torymid wasp, Megastigmus transvaalensis, originally reared from Rhus spp. in South Africa, was recovered from drupes of the terrestrial weed Schinus terebinthifolius in Florida. Collections of S. terebinthifolius drupes in Florida during a 2-year period indicated that M. transvaalensis was present at all 18 sites surveyed and this was the only insect that emerged from these drupes. Dissections of drupes collected during the winter fruiting period indicated that wasps damaged 23.5 ± 2.8% of the drupes during 1997–1998 and 38.5 ± 4.2% of the drupes during 1998–1999. During the spring fruit production period, 76.3 ± 3.6% of the drupes were damaged by the wasp in 1998 and 74.8 ± 3.4% during the same period of 1999. Germination tests of wasp-damaged drupes indicated that none of the infested seeds were viable. Purportedly diapausing wasps emerged more rapidly from rearing conditions that included a 12-h compared to a 14-h photoperiod. Utilization of alternate hosts was not detected despite attempts to rear the wasp from drupes of the native species within and outside the Anacardiaceae family found in the Florida range of S. terebinthifolius.