An Orchid Bee in Nicaragua (from whatsthatbug.com)

An Orchid Bee in Nicaragua (from whatsthatbug.com)

Here in New York the weather outside is February gray.  The buildings are gray.  The sky is gray.  The trees are gray.  The people are dressed in gray and black.  Fortunately we can beguile away this monochromatic tedium by contemplating the Euglossini, also known as the orchid bees!

Despite their Latin name, the Euglossini are not uniformly eusocial.  This means that most species of orchid bees live solitary lives (in marked contrast to honeybees–which live in vast hives more ordered than the strictest totalitarian state).  The orchid bees live in Central and South America, apart from one species which ranges into North America.  They are notable for their brilliant iridescent blue and green coloring.  The females build nests out of mud and resin.

Museum specimens of orchid bees

Museum specimens of orchid bees

The most remarkable aspect of Euglossini behavior is the male bee’s obsession which the aromatic compounds produced by various tropical orchids.  Male orchid bees have a rarified ability to sense these fragrances even in small quantities (like many heady floral/fruit scents the chemicals produced by the orchids are usually complex esters).  The bees harvest the molecules with front legs specially modified to resemble little brushes (and in doing so they generally pollinate the orchids, which are wholly dependent on the bees).  Astonishingly, the male bees store the chemicals in a cavity on their back leg which is sealed off and protected by waxy hairs.

English: An orchid bee, Euglossa viridissima sleeping on a leaf. Miramar Florida (by Efram Goldberg)

English: An orchid bee, Euglossa viridissima sleeping on a leaf. Miramar Florida (by Efram Goldberg)

The male bees appear to use these compounds when trying to attract a mate but no female attraction to the odors has been proved.  On the other hand, many Stanhopeinae and Catasetinae orchids are absolutely dependent on the male bees to reproduce.  Different species of these orchids rely on specific species of orchid bees to successfully pollinate far-away partners in the rainforest.  Charles Darwin wrote about this pollination system after observing it in the wild and later referred to the highly specialized orchids as proof of the ways in which species adapt to their environments.

Euglossa mixta (from The University of Arizona's Center for Insect Science Website)

Euglossa mixta (from The University of Arizona’s Center for Insect Science Website)