Temperature has a profound effect on the growth and development of ectothermic animals. However, the extent to which ecologically-driven selection pressures can adjust thermal plastic responses in growth schedules is not well understood. Comparing such responses between sexes provides a promising but underexploited approach to evaluating the evolvability of thermal reaction norms: males and females share largely the same genes and immature environments but experience different ecological selection pressures. In this study, we performed a meta-analysis of sex-specific thermal responses in insect development times. We show that sex-specific responses of development times to temperature variation are broadly similar. Moreover, sex differences in thermal plasticity are considerably less pronounced than sex differences in plastic responses induced by variations in larval diet. Our results point at the existence of substantial constraints on the evolvability of thermal reaction norms in insects, an essential aspect to consider in predicting evolutionary responses to climate warming.