On Thursday, she and 20 of Onas' 142 overnight campers planted a garden of bee-friendly flowers - phlox, speedwell, bee balm, Russian sage - near the camp's mini-farm of cucumbers, tomatoes, and corn. Fertilizer was provided in part by pet donkeys Pedro and Pepita.
"To me, that's a good smell," said Williams, 45, who walked around the garden in bare feet, toenails painted a purple that matched her sundress. "It's the smell of plants that will grow instead of die."
Last year, Williams, who lives in New York's Hudson Highlands region, performed at 11 summer camps throughout the Northeast. This year, she put Onas on the tour because her college roommate's daughter had attended it.
The 90-year-old Quaker program, on 72 acres in upper Bucks County, draws campers from as far away as Chicago and Washington.
Williams, whose latest CD is In the Time of Gods, performed Wednesday night at the camp's outdoor stage, then came back the next day to join Onas' master gardener, Lee Gould, in creating a food court for honeybees.
Nationwide, the bees' survival is threatened by a phenomenon known as colony collapse disorder, believed to be caused by a combination of factors including disease, parasites, and pesticides.
An estimated one-third of the world's food supply is dependent on pollination, much of it accomplished by honeybees buzzing from bloom to bloom. The honeybee is one of 25,000 bee species, but it is the most important for agriculture, said Edwin G. Rajotte, a professor of entomology at Pennsylvania State University and a researcher at its Center for Pollinator Research.
Williams' father, Gray, is a beekeeper, and she grew up surrounded by honeybees in Chappaqua, N.Y.
"That's the crowd I run with," Williams said of her eco-friendly friends and family. "They talk about this stuff at dinner parties."
Williams works hard to live sustainably. She and her family has a garden, and solar panels that produce 70 percent of their electricity; they use a masonry heat stove.
Williams decided to tour camps because young audience members told her they had first heard her songs at camp. It would be a perfect setting, she thought, for enlisting children in the bee-saving movement.
"Ever since I was young, I was scared of bees," said Sam Craig, 12, of Brooklyn, N.Y. "But I figured out that they won't hurt me if I don't hurt them, and we need to stop taking away their homes."
Sam sat with fellow campers in a barn while Williams answered bee questions.
Jamee Lockard, 12, also from New York, asked about plants that would attract bees. Phoebe Yates, 11, of Brooklyn, wanted to know if herbs were a favorite.
Williams suggested white clover and scabiosa, a flowering plant that is "beautiful" and like honey to a bee.
By planting bee-friendly plants, the campers were helping to combat what's known as a bee desert - long stretches where the insects have no flowers to turn to.
Williams advised the youngsters to visit nurseries and tell workers they are not afraid of bees and want to plant flowers to help them.
"And, if you think of any songs as [the bees] fly by, sing them," she said, "because that helps the bees, too."
Contact Kristin E. Holmes at 610-313-8211 or firstname.lastname@example.org.