The toxic effects of essential oils involve many factors, among which are the entry points of toxins (inhaled, ingested or absorbed) and which may have contact, fumigation and phagoinhibitory effects (Regnault-Roger 1997). We also found variation in toxicity depending upon the application method of the essential oils. The essential oils, especially C. citratus and Z. officinale, can be used as effective control for stored grain pests, and they may be applied either topically or by fumigation.