none The external morphology and the development of the immature stages of M. mediator Ha1. were studied. When newly laid, egg is hymenopteriform. During embryogenesis it becomes larger in size and pear-shaped. M. mediator passes through 2 larval instars. When newly hatched, the 1st-instar larva possesses a combination of mandibulate and caudate larval characteristics. After a short period of nutrition it is transferred to the vesiculate type. When left the host, the mature larva is apodous, hemicephalous with distinctly sclerotized cephalic structures. Anal vesicle is retracted into the body. Eight pairs of open spiracles lying in the 2nd thoracic and from the 1st to the 7th abdominal segments. The cocoon is elongated having longitudinal depressions.