Insects play a major role in any ecosystem and are also of extreme importance to the well-being of humans. Amongst others, they are pollinators that indirectly determine food security. On a more negative side, they can cause great crop damage and act as vectors for many diseases. It is thus of utmost importance to understand their biology. In this context a study was undertaken to analyze the temporal and spatial composition of arboreal insects along the Omaruru River in central Namibia. This river is one of the ephemeral rivers in Namibia, running along an east-west rainfall and altitudinal gradient. Three typical Namibian tree species (Acacia erioloba, Acacia tortilis and Faidherbia albida) were selected as host species and their canopies sampled over a period of one year. An anaesthetising insecticide, Pyrethroid, was used to fog the tree. Insects dropped onto plastic sheets suspended underneath each sample tree. This material was collected, stored in 70% Ethanol and then sorted and identified into relative taxonomic units (RTUs).