To investigate the insecticidal activity ofmarjoram, caraway and worm wood oils against the adults of Sitophilusoryzae(L.) (Curculionidae, Coleoptera) and the active anddiapausing larvae ofkhapera beetle Trogoderemagranarium (Everts) laboratory bioassay tests were conducted, at four to five concentrations of eachplant oil, of21days under 30 and 20 ±1°C. The results indicated that the mortality of tested insects increased with increasing the plant oil concentration,exposure period and temperature, where the complete mortality of S. oryzae adults was obtained at 1.5 and 1% (v/w) of the three tested oils, after 21 days exposure periods at 30°C.Data also revealed that at 20°C, the worm wood oil was the most toxic for the studied insects, and it gave LC_50s of 2.41, 2.90 and 0.21%foractive anddiapausing larvae ofT.granarium (after 14 days exposure period) andfor the adults of S.oryzae(after 3 days exposure period), respectively. Caraway oil was the most toxic at 30ºC against theactive and diapausing larvae of T. granarium.The adults of S.oryzaewere more sensitive to investigated plant oilsthan active anddiapausing larvae ofTgranarium. It can be concluded that marjoram, caraway and worm wood oils have a toxic activity against the two stored-product insects, S.oryzaeand T. granarium.