Second harmonic spectra emitted from 1054 nm laser‐produced plasmas have been observed in side‐ and backscattering and are shown to have angularly dependent, complex structures. Sidescattered spectra show regularly spaced (∼20 A˚) Stokes components at intensities above 5×1013W/cm2. The Stokes components are polarized and stronger in the plane of the polarization of the incident laser. These Stokes components are interpreted to be caused by a combination of electron plasma waves generated by the parametric decay instability and the subsequent electron decay instability. Backscattered spectra show additional finely spaced red‐shifted satellites above 4×1014W/cm2, indicative of the electron decay instability of plasmons generated from resonance absorption.