A 2-year demonstration study was conducted to compare the effectiveness of two sources of Encarsia formosa (EF) on the biological control of the sweetpotato whitefly (SPWF) (Bemisia tabaci Gennadius) on poinsettias (Euphorbia pulcherrima Wild.). Commercially produced EF were raised on the greenhouse whitefly (GHWF) (Trialuerodes vaporariorum Westwood), while the locally produced EF were raised on the SPWF. Results showed that SPWF populations were reduced considerably both years, and maximum nymph parasitism ranged from 60% to >80%. No large differences were observed in the ability of EF to control SPWF populations whether raised on SPWF or GHWF nymphs. This study suggests that there is potential for controlling SPWF populations on poinsettia by EF in conjunction with an integrated pest management (IPM) program.