Insecticidal effect of volatile oils from peppermint (Mentha piperita), basil (Ocimum basilicum), lemon (Citrus limon)   and orange (Citrus sinensis)   against two museum insect pests was evaluated by fumigation test.  Also, the effect of oils on the antennal segments and their sensilla was studied by using scanning electron microscope.  Results of the study revealed that peppermint oil offered the highest toxicity to adults and larvae of the black carpet beetle and cigarette beetle at LD₅₀ level.  Larvae of both species were more susceptible than adults to fumigant actions.  Among the four volatile oils, the orange oil was less toxic to adult and larvae of both species. Fumigation of the third instar larvae of tested insects with different volatile oils resulted in malformation and disorientation in of the antennal structures and their associated sensilla in the emerged adults.