Observations from the ISEE satellite have recently revealed interesting electrostatic bursts that are apparently hook-induced emissions stimulated by the combined action of a coherent whistler-mode wave and a simultaneously observed electron beam with an energy range of the order of 1 keV (Reinleitner et al., 1982). In order to seek a plausible generation mechanism and interpret this nonlinear phenomenon a computer simulation study was carried out. The code used is a 2 1/2-D electromagnetic particle code (EM2 code) following nonlinear motions of more than a half million particles in the 128¿128 grid space under the self-consistent fields. The results show an interesting two-beam jetting as a result of a trapping and subsequent detrapping process, yielding a strong electrostatic emission with k vector parallel to the external magnetic field. The nonlinear evolutions of the wave spectra and of particle distribution functions and their phase-space behavior are discussed in connection with the observed ES bursts.