The effects of a synthetic purine nucleoside analog, antiviral agent, acyclovir (ACV), on adult longevity, fecundity, and hatchability of a serious honeycomb pest, greater wax moth Galleria mellonella L. were investigated by adding 0.01, 0.1, 1.0, and 3.0% ACV into artificial and natural diets. Control larvae were reared on diet without ACV. The artificial diet containing the lowest level of ACV, 0.01%, raised egg production from a number of 12.9 +/- 0.6 to 163.2 +/- 1.3. The hatching rate of these eggs was increased from 49.2 +/- 2.4% to 68.2 +/- 3.2%. Higher concentrations of ACV in natural food significantly increased both egg production and egg hatching rate. Female reared on old dark combs as natural diet exposed to 1.0% of ACV produced 167.5 +/- 5.8 eggs with 93.2 +/- 6.8% hatched. This study emphasizes the importance of determining the dietary impact of an antimicrobial agent as a food additive to a particular species of insect before its using for dietary antimicrobial purpose.