  Whistler waves are intermittently present in the solar wind, while their
origin and effects are not entirely understood. We present a statistical
analysis of magnetic field fluctuations in the whistler frequency range (above
16 Hz) based on about 801,500 magnetic field spectra measured over three years
aboard ARTEMIS spacecraft in the pristine solar wind. About 13,700 spectra (30
hours in total) with intense magnetic field fluctuations satisfy the
interpretation in terms of quasi-parallel whistler waves. We provide estimates
of the whistler wave occurrence probability, amplitudes, frequencies and
bandwidths. The occurrence probability of whistler waves is shown to strongly
depend on the electron temperature anisotropy. The whistler waves amplitudes
are in the range from about 0.01 to 0.1 nT and typically below 0.02 of the
background magnetic field. The frequencies of the whistler waves are shown to
be below an upper bound that is dependent on $\beta_{e}$. The correlations
established between the whistler wave properties and local macroscopic plasma
parameters suggest that the observed whistler waves can be generated in local
plasmas by the whistler heat flux instability. The whistler wave amplitudes are
typically small, which questions the hypothesis that quasi-parallel whistler
waves are capable to regulate the electron heat flux in the solar wind. We show
that the observed whistler waves have sufficiently wide bandwidths and small
amplitudes, so that effects of the whistler waves on electrons can be addressed
in the frame of the quasi-linear theory.
