Investigated were the food and foraging activity of twelve free ranging adult aardwolves Proteles cristatus and their cubs. For most of the year aardwolves are nocturnal and feed almost exclusively on the harvester termite Trinervitermes trinervoides (Sjostedt). During winter however, it is usually too cold for termites to forage at night, so the aardwolf becomes more diurnal and supplements its diet by feeding on another harvester termite Hodotermes mossambicus (Hagen), which is mainly active by day and during the winter. Nevertheless, the aardwolf still suffers a food shortage during winter. This is evident from the weight loss (up to 20% of body weight) experienced by all animals during this period. It is argued that the aardwolf's distribution across Africa is determined by the availability of those Trinervitermes species which are active throughout most of the year.