Field evaluation for the acaricidal activity of jatropha (Jatropha curcas L.) and castor bean oils (Ricinus communis L.) against the nymphs and adults of the two-spotted spider mite, Tetranychus urticae on Alcea rosea L. conducted out in May 2016 on A. rosea in the experimental farm of the Faculty of Agriculture, Suez Canal University, Ismailia, Egypt. The fatty acids constituents of the two essential oils (from seeds) were identified by gas chromatography (GLC) analysis. The acaricidal activity of castor bean oil was higher than that of jatropha oil where the total population reduction rate of jatropha oil was 74.12% for adults and 75.19 % for nymphs. Total population reduction rate of castor bean oil was 77.32% for adults; while it was 82.91% for nymphs on A. rosea leaves. Regarding flowers, the total population reduction rate of jatropha oil was 68.74 % for adults; while it was 73.94 % for nymphs but population reduction rate of castor bean oil was72.33% for adults while it was 76.02% for nymphs. The major constituents of fatty acids identified by using GLC analysis in jatropha and castor bean oils were erucic (44.34%) and ricinoleic acid (41.75%), respectively. This study revealed that the essential oil of J. curcas and R. communis exhibited potent acaricidal activity against T. urticae which may be attributed to the presence of different bioactive compounds which may affect alone or in synergism.