Chemical baits corresponding to natural orchid fragrance chemicals were used to attract and sample male orchid bees in terra firme and flood plain forest sites on the Tambo-pata Reserve in south-eastern Perú. The study was conducted monthly for two years. A total of 38 species of bees was collected at these chemical baits, and although most species were collected from both habitats, 11 species were significantly more common in one habitat than the other. There was considerable variation in the number and types of chemicals to which each of the orchid bee species was attracted.
Two cycles of seasonal abundance occurred annually in the number of orchid bee individuals and species collected at the chemical baits. A major peak occurred a month following onset of the wet season, and a minor peak occurred during the dry season. Species body size was related to seasonal activity, but additional factors such as flowering phenology and nest parasites were also probably involved.
The number of orchid bee species found on the Tambopata Reserve was similar to the number found in forest sites of eastern and central Brazil, Costa Rica, and Panamá. This homogeneity in species richness is in marked contrast to other insect groups such as Odonata, Lepi-doptera, Asilidae (Diptera), Tabanidae (Diptera), and Cicindelidae (Coleoptera), for which the species numbers recorded on the Tambopata Reserve are the highest for any similar sized area in the world.