Powders obtained from dry ground leaves of Synzygium aromaticm (L) and Xylopia ethiopica were treated under laboratory conditions (26.4$pm;3^{circ}$ and 70-79% r.h) for their abilities to protect grains from damage by adult Rhizopertha dominica F and Sitophilus zeamais Motsch. The adult insects were reared and tested on whole maize grains. The powders were mixed with maize grains at different dosage levels ranging from 1-5% (wt/wt). S. aromaticum caused significantly higher mortality in the two insects than xylopia ethopica. Maize grains treated with 5% concentration of S. aromaticum caused 90 and 55% mortalities of S. zeamais and R. dominica respectively after 7 days, while X. ethiopica treated-grains caused 50 and 15% mortalities respectively at the same time. Five % concentration of S. aromaticum inhibited F1 progeny production and adult emergence of Sitophilus zeamais. Significantly lower number of F1 adults of R. dominica emerged from grains treated with S. aromaticum when compared to adult emergence from X. ethiopica-treated grains. The powders significantly increased the developmental period of the two insects when compared to the control except in X. ethiopica that had no significant effect on S. zeamais.