The founder and owner of a large cosmetics company, Janice Starlin (Susan Cabot), is disturbed when her firm's sales begin to drop after it becomes apparent to her customer base that she is aging. Scientist Eric Zinthrop (Michael Mark) has been able to extract enzymes from the royal jelly of the queen wasp that can reverse the aging process. Starlin agrees to fund further research, at great cost, provided she can serve as his human subject. Displeased with the slowness of the results she breaks into the scientist's laboratory after hours and injects herself with extra doses of the formula. Zinthrop becomes aware that some of the test creatures are becoming violent and goes to warn Janice but before he can reach anyone he gets into a car accident. He is thus temporarily missing and Janice goes through great trouble to find him, eventually managing and then transferring his care to herself. Janice continues her clandestine use of the serum and sheds twenty years' in a single weekend, but soon discovers that she is periodically transformed into a murderous queen wasp.

Director Corman was clearly influenced by Kurt Neumann's 1958 film The Fly. The Wasp Woman has the head and hands of a wasp but the body of a womanexactly the opposite of the creature shown in the film's poster. In Jack Hill's prologue, we see a slightly mad Dr. Zinthrop fired from his job at a honey farm for experimenting with wasps.