[Objectives]  To clarify the potential threat posed by the fall armyworm, Spodoptera frugiperda, to shallot and onion crops. [Methods]  The effects of raising S. frugiperda larvae on either shallots or onions on larval growth and development, and the amount of oviposition time spent by adult females on these two host plants, were compared. [Results]  S. frugiperda can successfully complete its life history on both shallots and onions but the larval period was significantly shorter on shallots. The preadult survival rate of S. frugiperda on shallots was significantly higher (0.77) than on onions (0.58). Although there was no significant difference in the adult preoviposition period (APOP) on either host plant the total preoviposition period (TPOP) was significantly longer on shallots than on onions. Although not significant, the fecundity and total longevity of S. frugiperda were higher on shallots than on onions. The intrinsic rate of increase, net reproductive rate and finite rate of increase of S. frugiperdaraised on shallots were significantly higher, and the mean generation time shorter, compared to those raised on onions. There were significant differences in the oviposition preferences of S. frugiperda for different parts of shallots and onion plants. Females preferred to lay eggs on onions, particularly on the middle and upper part of onion plants. [Conclusion]  Although S. frugiperda had high reproductive fitness on both shallots and onions, shallots are the more suitable of these two host plants for this species. Despite this, females preferred to lay eggs on onions rather than shallots. The results of this study contribute to the theory of coevolution between insect pests and host plants, and provide a scientific basis for assessing the risk of S. frugiperda to shallot and onion crops.