An electron temperature anisotropy T⊥e/T∥e>1 leads to excitation of three distinct modes, the whistler, the electrostatic, and the Z-mode instabilities, in collision-less plasmas at frequencies below the electron cyclotron frequency |&OHgr;e|. (Here perpendicular and parallel subscripts denote directions relative to the background magnetic field.) Two-and-one-half-dimensional particle-in-cell simulations are used to study the nonlinear consequences of the growth of these modes in homogeneous plasmas with &ohgr;e~|&OHgr;e|, where &ohgr;e is the electron plasma frequency. The simulations show that wave-particle scattering by enhanced fluctuations from the whistler and electrostatic anisotropy instabilities imposes a &bgr;-dependent upper bound on the electron temperature anisotropy at &bgr;∥e≤0.10. The simulations also demonstrate that the maximum value of the dimensionless fluctuating magnetic fields increases with &bgr;∥e and that at sufficiently low &bgr; the electrostatic instability leads to non-Maxwellian suprathermal enhancements on the reduced electron velocity distribution fe(&ngr;∥). ¿ 2000 American Geophysical Union