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The adult scarab beetle fauna of the canopy in a lowland tropical rainforest in southern Venezuela was observed and collected by means of a 42-m-tall tower crane for a complete year. This first census of an entire Amazonian canopy scarab community was embedded within the interdisciplinary research project "Towards an understanding of the structure and function of a Neotropical rainforest ecosystem with special reference to its canopy" organized by the Austrian Academy of Science. The Scarabaeidae represented one of the most species-rich beetle families in the canopy of the crane plot and were therefore selected for a detailed analysis of host-use patterns. Thirty-three species of Scarabaeidae with 399 individuals were recorded, including two species represented by singletons. Subfamilies abundant in the canopy were the Rutelinae, Dynastinae, and Melolonthinae. Species were diurnal or nocturnal flower visitors restricted in their occurrence to their host trees during the flowering season. The scarab beetles remained commonly on one host tree species throughout the entire flowering period and switched to another host tree species only after depletion of food resources. Some species fed on extrafloral nectar but feeding on fruits and leaves was uncommon in the observed species. Most species showed a broad host range, often with abundant species recorded on several host trees. Seven species were found exclusively on one tree species. The co-occurrence of up to five congeneric species sharing the same host trees and diet was conspicuous. With this study, it could be shown how species of Scarabaeidae track available food resources within the canopy of a tropical rainforest.

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