Fall armyworm, Spodoptera frugiperda belonging to family Noctuidae of order Lepidoptera, native to Americas. Recently, it has been reported from Pakistan as an invasive alien species and causing severe economic losses. An experimental study was conducted to check the occurrence, damage pattern and developmental parameters of this invasive alien species on maize. The biological studies showed that incubation period, total larval and pupal period were recorded 2, 10 and 7 days, respectively. Total life period from egg to adult was recorded 33-34 days (2 + 10 + 7 d) the range not given? on maize while a single female can lay about 289-300 eggs in her whole life duration. The larval weight and survival % were 0.545 g and 80 % on maize, respectively while pupal weight and survival % were recorded 0.123 and 76%, range respectively. The infestation of FAW was observed on maize in all study area. The percentage infestation was recorded 15-50% on maize. The results concluded that pest is very destructive for horticultural and agricultural crops in the study area. The current parameters can prove fruitful in the management of this emerging insect pest in the country (Pakistan).