Pyralid moths, such as Ephestia kuehniella (Zeller) or Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), are among the pests of most concern in mills and food industries worldwide. One option for their control, which presents an alternative to the application of insecticides, is the release of natural enemies. Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is a larval parasitoid of pyralid moths that is commercially available for augmentative release in storehouses. They are delivered as adults that limit their performance. To improve their quality when released at the target location, a banker box has been developed consisting of a rearing box that optimizes the release of the parasitoid. In the present study, the nonpest larvae Galleria mellonella (L.) (Lepidoptera: Pyralidae) have been used as a host, substituting for E. kuehniella larvae which were used in the previous design. The best results were obtained when a mixture of two larval sizes of the host were offered to the female parasitoid, producing five times more adults than with E. kuehniella larvae. Quality of the released parasitoids was optimal because they were delivered in the pupal stage inside the rearing box and adults began to emerge in situ. The banker box released adult parasitoids over a prolonged period of approximately 25 d at the target location. The use of this banker box may significantly help in the biological control of stored-product moths.