Larvae of Trogoderma inclusum exhibiting possible disease symptoms were forwarded to the Insect Pathology Laboratory, Entomology Research Division, ARS, for diagnosis. All showed protozoan infection. Some of the larvae contained spores of a schizogregarine, some oocysts of a coccidian, and some both spores and oocysts. Later the same schizogregarine organisms were found in larvae of T. glabrum in cultures maintained at the Stored-Grain Insects Laboratory, Manhattan, and in wheat in storage in other parts of Kansas. Cultures of supposedly healthy T. glabrum were sent from Manhattan to the Khapra Beetle Laboratory at Mesa, Arizona. However, the infection developed later and spread to the khapra beetle, T. granarium. At the suggestion of the Insect Pathology Laboratory, transmission studies were initiated at this laboratory. After larvae of T. inclusum were exposed 12 weeks in a medium supplemented by ground sickly larvae, 75% were moribund or dead. After a similar exposure to a medium supplemented by ground dead diseased larvae, the percentage increased to 92. It is suggested that the schizogregarine organism may have possibilities as a control measure for economically important species of Trogoderma.