In the ichneumonid wasp Hyposoter didymator, a polydnavirus was detected in the female reproductive tract. With the aim of studying the regulation of polydnavirus replication, the location and the structure of the virus-producing cells were determined, and the virus replication process was followed inside the ovaries of young adult females observed in light and electron microscopy. The examination of ovaries of pupa females revealed that virus replication is initiated within the calyx just prior to adult emergence. This study revealed that the calyx appears to be a specialized virogenic tissue which also has, during late pupal life, a secretory function that alters the function of virus production. none