Abstract: ResuIts of bioassays showed that the essential oils from Clausena dunnianawas very effective against stored product insects,Sitophilus zeamais and otherspecies.It caused 99.33 % of mortality and completely inhibited the reproduction ofred flour beetle(Tribolium castaneum)when was used for fumigation at a dosage of20 mg/L,or mixed with wheat flour at a concentration of 0.2% by weight.Estragole,the predominant component of the essential oil,was isolated by means of columnchromatography and proved to be the insecticidal component of this plant by aseries of bioassays.