Euglossini

Euglossine bees, also called orchid bees, are the only group of corbiculate bees whose non-parasitic members do not all possess eusocial behavior. Most of the species are solitary, though a few are communal, or exhibit simple forms of eusociality. There are about 200 described species, distributed in five genera: Euglossa, Eulaema, Eufriesea, Exaerete and Aglae, all exclusively occurring in South or Central America. The latter two genera are cleptoparasites in the nests of other orchid bees. All except Eulaema are characterized by brilliant metallic coloration, primarily green, gold, and blue.

Male orchid bees have uniquely modified legs which are used to collect and store different volatile compounds (often esters) throughout their lives, primarily from orchids (which do not supply pollen or nectar), and these chemicals are evidently exposed by the males at their display sites in the forest understory, where matings are known to take place. Although the accumulated volatiles may serve as a signal to females, female attraction or an effect on male mating success has never been demonstrated. The behavior is essentially unique in the animal kingdom. These volatile compounds are commonly used as bait to attract and collect these bees for study, and include many familiar flavorings and odors considered appealing to humans (e.g., methyl salicylate, eugenol, cineole, benzyl acetate, methyl benzoate, methyl cinnamate), and others which are not (e.g., skatole).

Neotropical orchids themselves often exhibit elaborate adaptations involving highly specific placement of pollen packets (pollinia) on the bodies of the male orchid bees; the specificity of their placement ensures that cross-pollination only occurs between orchids of the same species. Different orchid bee males are attracted to different chemicals, so there is also some specificity regarding which orchid bees visit which types of orchid. The early description of this pollination system was by Charles Darwin, though at the time, he believed the bees were females. Not all orchids utilize euglossines as pollen vectors, of course; among the other types of insects exploited are other types of bees, wasps, flies, ants, and moths.