[Objectives]  To investigate the relative effectiveness of different wavelength LED lights to trap Spodoptera frugiperda and Ostrinia furnacalis, and thereby provide a theoretical basis rationalize and optimize the use of LED insect traps. [Methods]  The relative effectiveness of six different single wavelength LED lamps, both individually and combined in pairs, were tested with respect to trapping S. frugiperda and O. furnacalis. Solar-powered LED insect traps with wavelengths in the range of 320-420 nm were used as the control. [Results]  The relative effectiveness of the single-wavelengths was 365>345>355>350 nm. Only the 365 nm lights caught significantly more of the targeted pest species than the control (P<0.05). The relative effectiveness of the combined wavelength traps was 365 nm+350 nm > 365 nm+355 nm > 355 nm+350 nm > 345 nm+355 nm. Only the 365 nm+350 nm lights caught significantly more of the targeted pests than the control. Further comparison of the effectiveness of single and compound wavelengths indicates that the wavelengths of 365 nm + 350 nm caught significantly more S. frugiperda and O. furnacalis than all other single, or combined, wavelength traps (P<0.05). [Conclusion]  LED insect trap lamps with wavelengths of 365 nm + 350 nm were the best for trapping S. frugiperda and O, furnacalis. These results lay a foundation for developing efficient and environmentally friendly LED insect traps.