Caste development in social Hymenoptera represents a prime example of phenotypic plasticity and variation in life histories and is best understood in honey bees. We review the larval feeding regimes and major signalling pathways involved in the divergent developmental trajectories. The role of juvenile hormone (JH) is discussed with an emphasis on the regulation of JH synthesis, degradation and the molecular mode of JH action. As there are apparent inconsistencies between the expression of insulin, TOR and Egfr pathway genes and larval growth rates, we propose that the circuitries and integration of these nutrient-sensing pathways have been remodelled in social evolution. A potential integrator of nutrient sensing with growth regulation is the hypoxia response, indicating that regulation of oxidative metabolism, possibly through epigenetic effects, is a major determinant of caste fate. Finally, we compare signalling pathways acting in larvae and adult females, with a special emphasis on the role(s) of vitellogenin. [ABSTRACT FROM AUTHOR]