Katacamilla cavernicola Papp, collected from caves at four localities in northern and central Namibia, is here shown to exhibit both parietal and troglophilic habitat preferences, and the larval stage is trophically guanobious. Katacamilla cavernicola was reared in the laboratory from the guano of the rock pigeon Columba guinea L. (parietal), and of the common slit-faced bat Nycteris thebaica Geoffrey (troglophilic) and larvae and puparia were obtained. The duration of the larval stage of K. cavernicola was found to be 7 days and the pupal stage 6-7 days, eggs remaining dormant within guano, and larval development being apparently triggered by periodic moistening, either by urine, or other liquids. Descriptions of the third instar larva and puparium are presented and are illustrated with line drawings and stereoscan micrographs. These descriptions of the immature stages are the first known for the Camillidae. Larval features are compared to the three closely related families in the Ephydroidea, for which the immature stages are known: Drosophilidae, Curtonotidae and Ephydridae. The larval morphology of Katacamilla is found to be generally close to the putative groundplan for the Ephydroidea. However, the basal sclerite has very large open windows with the ventral arm of the dorsal cornu being very long and needle-like. The thoracic segments are very long and slender and unusually well-separated from one another, and the abdominal segments and the prothoracic Keilin organs are very close together, a trait that is within the Ephydroidea currently only known in the Ephydridae. Keywords: Diptera, Ephydroidea, Camillidae, Katacamilla, Cavernicola, Namibia, Cavernicolous, Biospeleology, Immature Stages, Larval Morphology.