  In this paper, we develop the modulation analysis, the perturbation argument
and the Virial identity similar as those in \cite{MartelM:Instab:gKdV} to show
the orbital instability of the solitary waves $\Q\sts{x-ct}\e^{\i\omega t}$ of
the generalized derivative nonlinear Schr\"odinger equation (gDNLS) in the
degenerate case $c=2z_0\sqrt{\omega}$, where $z_0=z_0\sts{\sigma} $ is the
unique zero point of $F\sts{z;~\sigma}$ in $\sts{-1, ~ 1}$. The new ingredients
in the proof are the refined modulation decomposition of the solution near $\Q$
according to the spectrum property of the linearized operator $\Scal_{\omega,
c}"\sts{\Q}$ and the refined construction of the Virial identity in the
degenerate case. Our argument is qualitative, and we improve the result in
\cite{Fukaya2017}.
