Robbing Nectar

May 3, 2013

Robbing Nectar

May 3, 2013

We all take short cuts--short cuts around the campus, to the beach, to a favorite restaurant...

Honey bees take short cuts, too.

We've often watched assorted bumble bees and carpenter bees drill a hole in a long-tubed flower to rob the nectar.

And we've watched honey bees benefitting from this behavior.

Today we observed a carpenter bee, Xylocopa tabaniformis orpifex, engaging in nectar robbing in salvia at the UC Davis Arboretum.  Nectar robbing occurs when a bee or other animal circumvents the usual plant-pollinator relationship and "cheats" by entering a flower from the outside to steal nectar, thus avoiding pollination or contact with the anthers.

There's excellent information on bumble bees, their habitat needs, their behavior, and identifying characteristics in a free, downloadable PDF from the Xerces Society for Invertebrate Conservation: "Conserving Bumble Bees: Guidelines for Creating and Managing Habitat for America's Declining Pollinators."

The PDF mentions that "short-tongued bumble bees will engage in 'nectar robbing' from flowers with a long corolla tube by biting holes at the base of the corolla and drinking the nectar from the outside of the flower." The bee grabs the reward but doesn't contribute to "the plant's pollination needs."