Psammoduon deserticola (Simon) (Araneae: Zodariidae) is a spider adapted to live in the sandy environments of the Namib Desert. The individuals dive through the sand thus avoiding high temperatures and to find their prey. Several major desert habitats were sampled along transects crossing a dune, inter-dune valley, riverbed and a gravel plain. This indicated that several biotic and abiotic factors influence spider density, namely the occurrence of rain, soft sand, vegetation cover and prey. Food preference and predation were studied in laboratory experiments. The larvae of Tenebrionidae (Coleoptera) proved to be the most important food source for P. deserticola, while larvae of Syrphidae (Diptera) were less preferred. Lepidoptera larvae were not preyed on at all, while Thysanura were an occasional supplementary food source. As predators of tenebrionid larvae, P. deserticola may play an important role in the food web of the Namib Desert dunes.