Honey bees, bumble bees, hover flies, parasitoids and common houseflies aren't the only visitors paying their respects to our two nectarine trees.

A picture-winged fly (Ceroxys latiusculus) dropped in on Feb. 28 for a quick visit.

About the size of a common housefly, it's known as a nuisance pest that hangs around the house more than it does around nectarine trees.

Little is known about is biology, says entomologist Whitney Cranshaw of Coloradio State University.  Its larvae often develop within the seed heads of Senecio, a genus of the daisy family that includes ragworts and groundsels.

It’s often mistaken for a walnut husk fly.

This one crawled up and down the nectarine blossoms as if mimicking a bee.

In a wing beat, it was gone.

Xerces Society scientists just developed a first-of-its-kind conservation strategy summarizing the threats facing native bees in the diverse landscapes of Yolo County and identifying measures to protect them.

And what a great conservation--and conservation--piece this is.

Their 70-page paper, Yolo Natural Heritage Program Pollinator Conservation Strategy, is designed to protect such wild bees as bumble bees, leafcutter bees, mason bees, blue orchard bees and others. (You can download the paper from the Xerces Society Web site and from the Yolo Natural Heritage Program Web site.)

“Whether you manage roadsides or run a farm there are actions that you can take to improve the health of pollinators,” says Matthew Shepherd, Xerces Society senior conservation associate and co-author of  the report.  “Identifying and protecting floral resources can provide significant benefit to the native bees and other pollinators in Yolo County.”

The project, funded in part by a grant from the California Department of Fish and Game, provides land managers with information vital to "save the pollinators" of Yolo County. The county includes six major landscapes: agriculture, grasslands, woodlands, shrubland and scrub, riparian and wetland, and urban and barren.

As the scientists point out, some 60 to 90 percent of the world's flowering plants depend on animals for pollination, and most of these animals are insects.

"Research shows that native bees contribute substantially to the pollination of many crops, including watermelon, canola, sunflower, and tomatoes," the report says. "The value of crop pollination by native, wild bees in the United States is estimated at $3 billion. In Yolo County, extensive studies demonstrate the significant role of native pollinators in the economic viability of agriculture. In addition, native bees provide incalculable value as pollinators of native plants."

Among the many contributors to this report: native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis; and UC Berkeley conservation biologist Claire Kremen, an affiliate of the UC Davis Department of Entomology.

This is a report well-worth reading, and even more importantly, following the measures listed to protect the health of our native bees. These beneficial insects need flowers for foraging and nest sites to raise their young. Some 70 percent of native bee species nest in the ground. Most of the others nest in cavities in trees or plant stems. "Bumble bees require a small cavity such as an abandoned rodent hole," the report indicates.

So, that black-faced bumble bee (Bombus californicus) that you see gathering pollen on a California poppy may go home to...well...a rat hole. 

All the more reason to become more observant and pro-active of their needs.

Research entomologist Terry Griswold of the USDA-ARS (U.S. Department of Agriculture, Agricultural Research Service) drew a capacity crowd when he spoke recently at UC Davis on "Patterns of North American Bees at Scales Plot to Continental: Rare Is Common?"

His talk, in 122 Briggs Hall, Kleiber Drive, attracted entomologists, pollination biologists, apiculturists and others interested in North American bees.

Now folks can tune and and watch the Webcast, compliments of the UC Davis Department of Entomology.

Under the direction of professor James Carey, the entomology seminars are being Webcast by his graduate students, James Harwood and Amy Morice, and posted online. 

Just access the Webcast page to tune in.  There you'll find other Webcasts, also video-taped by Carey's graduate students.

Ants, beetles, butterflies, bumble bees, honey bees, midges, thrips and more...from the graduate students to you.

Folks accustomed to seeing only honey bees (which are non-natives) buzzing around their yard probably aren't aware that in the United States alone there are some 4000 identified species of native bees.

And they probably aren't aware of The Bee Course. 

That's a workshop offered for conservation biologists, pollination ecologists and other biologists who want to gain greater knowledge of the systematics and biology of bees. It's held annually in Portal, Ariz. in the Chiricahua Mountains at the Southwest Research Station of the American Museum of Natural History (AMNH). This year's dates are Aug. 22-Sept. 1.

Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, and active in the Xerces Society, has taught at The Bee Course since 2002.

The course, led by Jerry Rozen of AMNH, has been operating continuously since 1999, Thorp said, and UC Davis graduates are very much involved. Steve Buchmann who received his Ph.D. at UC Davis in 1978, is one of the instructors. Ron McGinley who received his undergraduate degree at UC Davis, does most of the initial student contact and scheduling for the course, Thorp said.

"There are usually about eight instructors and 22 participants for the 10- day course," Thorp said. "Most of the time is spent in the lab identifying bees to genus.  At least three days are spent in the field so students can see various bees doing their thing, collect them and bring them back to the lab to ID them.  It is a great experience for students to interact with instructors and especially with their peers from round the world."

"Instructors all donate their time to teach in the course, but benefit from the chance to get together with colleagues and a new cohort of interesting students each year.  Every class is different--that is, it takes on its own personality--and each student brings something new and different to the mix."

More locally, Thorp will speak Sunday, March 7 on the amazing diversity of native bees at the 2010 Bee Symposium, sponsored by the Santa Rosa-based Partners for Sustainable Pollination (PFSP). He'll discuss their nesting habits and nest site requirements. The symposium takes place from 9 a.m. to 5 p.m. in the Subud Center,  234 Hutchins Ave., Sebastopol.

The fourth annual conference will offer updates and new perspectives on honey bees and native pollinators, according to PFSP executive director Kathy Kellison. 

It's good to see the focus on native bees as well as honey bees. For more information on native bees, be sure to check out the Xerces Society Web site and UC Berkeley's Native Bee Gardens.