Lipotriches (Plain Sweat Bee)

From the U.S. Geological Survey (USGS):

Bee Butts — Well, we may not "Break the Internet" with this one, but we like bee butts and we cannot lie! 

This is backend of a Lipotriches (Plain Sweat Bee) collected in Australia. This is one of the bees in which the males are known to form sleeping aggregations – small groups to dozens of individuals clustering together on the same twig late in the afternoon and remaining there until after dawn. There may be quite a lot of “jockeying for position” as males alight too close to another individual with low key aggressive interactions. Some clusters might contain more than one species. There has been little research on the reason for this aggregating behavior, although safety in numbers might play a role.

You can find more bees, all for public domain use, from our Bee Inventory and Monitoring Lab athttp://flickr.com/photos/usgsbiml.