Red flour beetle Tribolium castaneum (Herbst) is a major pest of stored products. The aim of this study was to assess the potential fumigant effects of 1,8-cineole, essential oil component, on the T. castaneum pupae. The compound was tested in 6 doses; in two treatments (fumigation without grain and with wheat grain), exposed for 48 h, in 4 repetitions, for each gender. The compound 1,8-cineole had lethal effect on the treated pupae at both genders and in the both treatments. Total proportion of the normally developed beetles was decreased. In addition, 1,8-cineole had also a growth regulator effect, producing adultoids and deformed units, with males more susceptible. In the treatment with the grain there were significant lower dead pupae, normally developed live male beetles and also deformed female units in the stage 2. In general, compound 1,8-cineole has multiple effect against T. castaneum in pupal stage.