As the crowd drifted away from the shaded clearing at the Boston Nature Center in Roslindale, Sage Radachowsky crouched, pressed his ear to the chest-high stack of white, painted wooden boxes, and listened.

“There’s a hum, a whir,’’ said Radachowsky, an evolutionary biology researcher at Harvard. “And then there are single notes.’’

The entomological orchestra emanated from tens of thousands of honeybees, busy socking away nectar, building combs, and reproducing in the late-summer rush to prepare for another Boston winter, when at least 30 percent of their ranks will be wiped out by cold or pests.

Radachowsky, 37, of Roslindale is among a growing group of urban and suburban beekeepers who have taken up the age-old practice of tending to hives, harvesting honey and wax, and quietly boosting an endangered biological process on which our food supply depends.

“It’s just beautiful to see them going in and out of their hive every day,’’ said Radachowsky, who was among more than 30 amateur beekeepers, bee enthusiasts, and naturalists who gathered yesterday on National Honeybee Day for a 9-mile “Tour de Hive’’ bike trek, visiting apiaries from Mattapan to Brookline.

“It’s like having 40,000 friends,’’ he said.

Organizers of the tour, sponsored through the local chapter of the Northeast Organic Farming Association, hope the event will serve as an entree into a world that can turn quickly from fascinating hobby into all-out passion, leading many to snatch up starter hives and put on protective face veils for their own backyard efforts.

The lure, enthusiasts say, centers on the microcosm of the hive, a miniature world many amateur beekeepers find highly rewarding - and at the end of a successful season, delicious.

But it’s frequently not the viscous, sweet substance that draws in the novice beekeepers.

Colony collapse disorder, a mysterious threat to large bee populations that has wiped out apiaries across the country, has drawn considerable attention in recent years, as awareness has spread of the deeply intertwined relationship between the tiny insects and most of the food that feeds the world.

“Honeybees do 75 percent of all pollination of our crops,’’ said Rick Reault, owner of New England Beekeeping Supplies in Tyngsboro. “They’re responsible for a third of every spoonful of food we eat.’’

In the past three years, Reault estimated that about 1,000 new amateur beekeepers come to him each year to purchase supplies or attend workshops, many drawn by the environmental benefits, some by the challenge, and others by the spiritual balm.

“Its almost like zen, beekeeping,’’ said Jean-Claude Bourrut, 48, an organic farmer and beekeeper at the Natick Community Organic Farm who was principal coordinator of the tour. “You feel like you’re in communion with the bees. They have that therapeutic impact on you. It’s like being in communion with nature at large.’’

While many hobbyist beekeepers do it for the honey harvest, commercial beekeepers play a key role in agriculture nationwide.

Bees pollinate most plants, including corn, grains, and grassy plants that feed beef cattle and other livestock.

While the mom-and-pop backyard apiary can require as little as a wooden box and a half-dozen inner frames that hold the honey comb, commercial bee operations often have hundreds of hives that demand treatment with heavy chemicals, pesticides, and nutrients not found in the wild - practices that Bourrut shuns as an organic beekeeper.

During the high growing seasons, he said, the biggest apiaries pack their colonies into tractor-trailers and follow the crops from region to region as they mature, pollinating almond trees in California, apples in western Massachusetts, and blueberries in Maine.

“There is no money, currently, in honey,’’ said Bourrut. “The money is in pollination.’’

For at least one onlooker yesterday, donning the veil was highly personal.

Milo Medunic, 29, of Medford, discovered only recently that his last name translates in old Slavic as “honey keepers.’’

“So I want to keep that going,’’ he said.

Before his family fled from the former Yugoslavia, he said his father used to keep bees, and he has early memories of chewing on a hunk of wax comb as he watched the men extract honey. Now he plans to start his own colony soon.

“It just comes together as a positive experience all around,’’ he said. “You get fruit, you get flowers, and then a hobby, that no one else can say, ‘I’m a beekeeper.’ ’’

Matt Byrne can be reached at mbyrne.globe@gmail.com

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