The wavelength dependence of electron localization of H_{2}^{+} and its isotopomers in the ultraviolet pump-probe scheme is investigated by numerically solving the time-dependent Schrödinger equation. By combining with a semiclassical method, an effective analytical formula expressed in the adiabatic representation is established to describe the localization probability with several zero crossings. A stable zone with respect to the laser intensity and carrier envelope phase is found at a relatively long probe wavelength. Finally, the critical probe wavelengths to reach at the stable zone are derived by using the three-dimensional model. Slower nuclear motion of heavier isotopomers leads to a longer critical wavelength.