Many animals go through a larval stage during their lifecycles, and this period of development is often quite plastic in response to environmental change. Ilya Ruvinsky and colleagues have previously shown that Caenorhabditis elegans hermaphrodite larvae that are exposed to male pheromones exhibit accelerated development. Here, they explore this phenomenon in more detail and show that this acceleration applies to both somatic and germline development during larval stage 4 (L4), with exposure to male pheromones hastening processes that include seam cell divisions, gonad growth and germline progenitor cell expansion. Exposure to male pheromones also results in larvae spending less time in the quiescent phase between larval stage 3 (L3) and L4, which means that they spend more time feeding before entering the L4 stage. This extended feeding period may explain why L4 development happens at a faster pace. The authors define a crucial period in L3 during which the larvae can respond to the pheromones. Similar sensitive periods in other stages reveal iterative and coordinated organisation of behaviour and development that permits plasticity of larval development in C. elegans. These findings could have implications for developmental plasticity in the larvae of other species.