If you have a patch of salvia (sage) growing in your yard, watch for the nectar robbers.
Carpenter bees are among the insects that engage in nectar robbing. They drill a hole in the corolla of the flower, circumventing the usual plant-pollinator relationship. In other words, they're “cheating” pollination by "stealing" the nectar. Scientists call this "robbing the nectar."
The most prevalent nectar robbers in our yard are the mountain carpenter bees, Xylocopa tabaniformis orpifex. They're better at drilling holes than the Texas oilmen.
If you watch closely, you may see a honey bee following the carpenter bee around. She's taking the easy way out, finding the hole pierced by the carpenter bee and then gathering nectar to take back to her colony.
If a flower could communicate, it would probably say something like "Hey, you're doing an end run to get my nectar. Please don't use the side entrance--I have a front door."
Look at the Xylocopa on the Xanthorrhoeaceae.
If that sounds like a mouthful, think of the mountain or foothill carpenter bees, Xylocopa tabaniformis orpifex, on bulbine from the genus Bulbine in the family Xanthorrhoeaceae.
Carpenter bees and honey bees are among bees attracted to the yellowish-orange flower with bearded stamens. A native of South Africa, it's also known as yellow bulbine, snake flower and cat's tail.
The carpenter bee below is a male nectaring on Bulbine frutescens.
Bulbine is blooming now in the Häagen-Dazs Honey Bee Haven, a half-acre bee friendly garden planted in 2009 by the Harry H. Laidlaw Jr. Honey Bee Research Facility on Bee Biology Road, UC Davis.
The garden, owned and operated by the UC Davis Department of Entomology and Nematology, is open from dawn to dusk for self-guided tours. Admission is free. The art that graces the garden is the work of the UC Davis Art/Science Fusion Program.
The garden's mission: to provide a year-around food source for the bees at the Laidlaw facility and other pollinators; to draw attention to the plight of the bees; and to give visitors an idea of what they can plant in their own gardens.
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."
Meet a carpenter bee.
This one (below) is a male carpenter bee, Xylocopa tabaniformis orpifex, as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis.
It's also called a "mountain" or "foothill" carpenter bee.
When it slits the corolla of the flower--in this case, salvia--and bypasses the pollination process--this is called "nectar robbing."
The mountain/foothill carpenter bee is the smallest of the three species of carpenter bees in California, Thorp says. The other two are the Valley carpenter bee, Xylocopa varipuncta, the largest, and the California carpenter bee, Xylocopa californica, the second largest.
The male of the Valley carpenter bee is a green-eyed blond and often referred to as a "teddy bear." The female of that species is solid black. And huge!
The California carpenter bee or Xylocopa californica is known for its distinctive distinctive bluish metallic reflections on the body, Thorp says. The females have dark smokey brown wings.
The one photographed below, Xylocopa tabaniformis orpifex, is common in the center of the Central Valley, "probably due primarily to increased nest sites such as redwood arbors and fences," Thorp says. Although considered a pollinator instead of a pest, "it can be a pest when it gets into untreated redwood used for water tanks or structural timbers," Thorp points out. "The females are black with light smokey-colored wings. The male has bright yellow marks on the lower part of its face and some yellow hairs on the top front of its thorax."
You can see the yellow hair on the thorax.
And how big is the smallest of the three carpenter bees? "Much larger than a honey bee, but about half the size of the other two carpenter bees," Thorp says.
So you're sitting in your yard having your morning coffee, and you get buzzed--not a buzz from the caffeine but a buzz by a carpenter bee.
A male carpenter bee, Xylocopa tabaniformis orpifex, is guarding the salvia, fending off all other male suitors as it waits for a female to arrive. Then, seeking a quick energy fix, our subject stops to rob the nectar (when carpenter bees slit the corolla, bypassing the pollination process, it's called "robbing the nectar").
We managed to photograph this male carpenter (below) in quick succession: (1) in flight (2) stealing the nectar and (3) jumping off the flower.
Xylocopa tabaniformis orpifex is the smallest of the three carpenter bee species found in California, according to native pollinator specialist Robbin Thorp, emertius professor of entomology at UC Davis. The other two species: X. varipuncta and X. californica. (See UC Davis Department of Entomology website.)
X. tatabaniformis orpifex may be the smallest, but you wouldn't know it by its buzz.