  Kinetic simulations and theory demonstrate that whistler waves can excite
oblique, short-wavelength fluctuations through secondary drift instabilities if
a population of sufficiently cold plasma is present. The excited modes lead to
heating of the cold populations and damping of the primary whistler waves. The
instability threshold depends on the density and temperature of the cold
population and can be relatively small if the temperature of the cold
population is sufficiently low. This mechanism may thus play a significant role
in controlling amplitude of whistlers in the regions of the Earth's
magnetosphere where cold background plasma of sufficient density is present.
