The fall armyworm (FAW), Spodoptera frugiperda, is an invasive migratory pest that prefers to feed on crops of the Gramineae family such as maize and wheat. It has been recorded in different locations in China since its invasion in 2019. To assess its effect on different wheat tissues and to provide a risk evaluation for wheat fields, FAW larvae were reared on the wheat seedling (WS), spike (SPK), peduncle (PDC), flag leaf blade (F-b), and blade of the first leaf under flag (F-1b). The population parameters were recorded, and the data were analyzed using the age-stage, two-sex life table method. The results showed that the FAW achieved successful development on all the substrates, although those fed on F-1b grew the slowest, had the smallest pupal weight, and deposited the fewest eggs. The larval survival rates of those fed on WS, SPK, and PDC were more than 80%, while for F-b and F-1b they were 56.58% and 32.03%, respectively. Feeding on leaf blades also resulted in lower fertility, reproductive capacity, life expectancy, net reproductive rate, intrinsic rate of increase, and finite rate of increase. These results indicated that feeding on WS, SPK, and PDC were more beneficial for development compared to F-b and F-1b alone. However, leaf blades alone can still support the full FAW lifecycle and thus could play an important role in nutrition, especially when quantities of the preferred host tissues are not sufficient. These results provide guidance for assessing the FAW risk in China.