Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) is one of the most important predators used in the augmentative biological control of aphids worldwide. However, due to its particular life history, mass rearing A. aphidimyza remains difficult. Our results show that a high relative humidity level during pupation optimizes the development of A. aphidimyza. By improving humidity levels during pupae storage, we improved the production efficiency and nearly achieved a 100% adult emergence rate. These results allow us to suggest a new rearing method for the aphid predator A. aphidimyza.