Ball lightning is widely concerning because it is hard to detect, predict, and reproduce. The dependences of electromagnetic (EM) solitons, which are considered expectant ball lightning, forming at the wavelength of the incident light are investigated with two-dimensional particle-in-cell simulations. It shows that both the long wavelength microwave and the short wavelength laser are not suitable for producing the observed ball-lightning-like EM solitons. A strong field terahertz wave is proposed to inject and generate EM solitons. This paper can provide some references for researchers studying ball lightning.