Sometimes you get lucky.

While watching floral visitors foraging last week in our rock purslane (Calandrinia grandiflora), we noticed a tiny black bee, something we'd never seen before.

Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the UC Davis Department of Entomology, identified it as a female leafcutting bee, Megachile gemula, "which has an all-black form."

It's a rather uncommon bee, but a distinctive bee, said Thorp, who is one of the instructors of The Bee Course, offered every year in the Southwestern Research Station, Portal, Ariz.,  for conservation biologists, pollination ecologists and other biologists who want to gain greater knowledge of the systematics and biology of bees. Participants come worldwide to learn about bees.

Megachile gemula is native to the United States. The females snip round holes in leaves and line their nests with the material.  From egg to larva to pupa, a new generation emerges from the sealed nest. 

Meanwhile, if you want to go on a walking tour with Thorp, mark your calendar for Friday, June 22. Thorp will lead a Tahoe National Forest Service tour of native plants and pollinators in the Loney Meadow, near Nevada City, Nevada County. The tour, free and open to the public, will take place from 10 a.m. to approximately 2 p.m.

The walk is provided as part of the Forest Service Pacific Southwest Region’s 2012 Pollinator Special Emphasis Area "which has been developed to call attention to the importance of butterflies and native bees in providing important services for food production and ecosystem health," said Kathy Van Zuuk, Yuba River Ranger District botanist and forest level non-native invasive plant coordinator. 

And what bees might tour participants encounter? Probably bumble bees, mining bees, digger bees, leafcutting bees, mason bees and cuckoo bees, Thorp said. Other floral-visitors are expected to include flies, butterflies, and beetles, he said. Van Zuuk and fellow botanist  Karen Wiese will identify the native plants.

Those interested should meet at 10 a.m. at the Sierra Discovery Trail parking lot located off Highway 20 to carpool to Loney Meadow (where parking is limited). Participants of all ages should bring water, snacks, insect repellent, sunscreen and wear suitable footwear. (No dogs, please.)

Further information is available by contacting Van Zuuk at (530) 478-6243 or emailing her  at kvanzuuk@fs.fed.us.