  We identify a new dust instability that occurs in warped discs. The
instability is caused by the oscillatory gas motions induced by the warp in the
bending wave regime. We first demonstrate the instability using a local 1D
(vertical) toy model based on the warped shearing box coordinates and
investigate the effects of the warp magnitude and dust Stokes number on the
growth of the instability. We then run 3D SPH simulations and show that the
instability is manifested globally by producing unique dust structures that do
not correspond to gas pressure maxima. The 1D and SPH analysis suggest that the
instability grows on dynamical timescales and hence is potentially significant
for planet formation.
