Sperm structure and ultrastructure of Hermetia illucens was determined by light microscopy and transmission electron microscopy. The main sperm components were similar as for other Dipteran subspecies, while the ultrastructure revealed distinguishing features in the zone of overlap and anterior flagellar region. Sperm varied in size indicating sperm polymorphism. The head region is lacking an acrosome. The zone of overlap consisted of uniquely organized centriolar adjunct material, partly forming electron dense areas to finally form an outer ring separating the mitochondrial derivatives from the 9 + 9 + 2 axoneme. Accessory bodies arising from the zone of overlap are flanked by smaller to large mitochondrial derivatives into the anterior flagellum. This study confirms sperm structure diversity between brachyceran subspecies and support its relationship with nematoceran subspecies.