Galleria mellonella L. larvae were reared on a standard diet amended with varying concentrations (0, 0.0015, 0.015, 0.15, and 1.5%) of the benzimidazole-derivative antihelmintic drug oxfendazole. Survivorship, developmental times, longevity, fecundity, and fertility were monitored over the treatments. Relative to the untreated control, exposure to diet containing 1.5% oxfendazole significantly decreased survivorship in larval, pupal, and adult stages, prolonged the time to reach the adult stage, and reduced adult longevity. Oxfendazole at all concentrations significantly lowered egg production per female and decreased egg hatch. These results demonstrate that this antihelmintic may be explored as a candidate for insect pest control.