Senescence of neural stem cells is exquisitely regulated to ensure production of appropriate numbers of neurons that can vary drastically in different neuronal lineages. For instance, while neurogenesis ends in most Drosophila brain regions around pupation, the four pairs of mushroom body (MB) neuroblasts incessantly make neurons throughout pupal development. It is unclear what intrinsic and/or extrinsic mechanisms underlie the differential senescence of neural stem cells. We have uncovered that most, if not all, cerebral neuroblasts express the Imp and Syp RNA-binding proteins in opposite temporal gradients that show distinct lineage-characteristic temporal dynamics. The reciprocal Imp/Syp temporal gradients are steep and progress rapidly in non-MB neuroblasts, but get stretched into very shallow profiles in those long-lived MB neuroblasts. Here we report that the lineage-characteristic temporal profiles of Imp and Syp control when particular neuroblasts end in a lineage-autonomous manner. We further demonstrate that Imp and Syp act sequentially through distinct effectors to stop neurogenesis. Taken together with their known roles in specifying serially derived neuronal types, we propose that the opposing Imp/Syp temporal gradients constitute an evolutionally conserved stem cell aging program that govern both the length of neuronal lineages and the diversification of neuronal temporal fates.