  Skyrmions dynamics in the approximation of point-particle skyrmions is
considered in the multiferroic insulators, where the spiral magnetic structure
is accompanied by finite electric dipole moment. The skyrmion motion is studied
in the gradients of perpendicular magnetic and electric fields. The nonuniform
magnetic field with a fixed gradient magnitude leads to the spiral motion,
where skyrmion circulates in the plane perpendicular to the direction of
magnetic field. The frequency of circulation is fixed by the derivative of the
external magnetic field and the magnitude of the dipole moment. Application of
additional electric field which perpendicular to the magnetic field, but their
gradients have same direction leads to the drift motion of skyrmions resulting
in the magneto-dipolar Hall effect. Hydrodynamics of the gas of interacting
skyrmions in crossed nonuniform electric and magnetic fields shows the new type
of hydrodynamical instability caused by the drift motion. Three regimes of
instability are described.
