Particle simulations are used to investigate the effects of plasma sheet convection into regions of increasing tail lobe magnetic field strength on the stability of a magnetotail equilibrium. The self-consistent treatment of convection first drives Bz to zero on axis in the region of the strongest lobe field Bx and then causes the equilibrium to break due to the rapid growth of tearing modes driven by the induced temperature anisotropy. The net result is the evolution of the inward-convecting plasma sheet into a slowly moving or stagnant plasmoid. The time scale for this process is much more rapid than that associated with particle drift losses across the tail. These result support the suggestion that steady convection within the plasma sheet may not be possible. ¿American Geophysical Union 1990