Under blue skies, where low-rolling hills rise south of the Canadian border in the tiny town of Adams, N.D., a couple braves the stench of old honey, wax, smoke and bee muck.

Nancy and Keith Budke, married 43 years, are migratory beekeepers. They produce honey with the taste of canola nectar, sweet clover and other flowers that their bees pollinate first in North Dakota, then in Texas, after being hauled there by truck, and eventually in California — if the bees make it that far and if nobody snatches them.

This season, the chances of the bees making it to California were much lower. Honeybee colonies are under siege across much of North America. And the Budkes, owners and operators of Budke Bees, a small commercial beekeeping business, know it all too well. Parasites, loss of habitat, climate change and pesticides threaten to wipe out as much as 70 percent or more of the nation’s honeybee colonies this year, potentially the most devastating loss that the nation has ever seen.

“There is a shortage of bees across the entire world,” Ms. Budke said. “It’s a crazy life that we lead because we’re trying to fight so many different battles.”

At the start of their annual migratory journey last August, the Budkes had 2,900 hives. Larger operations manage 10 times as many. But the challenges faced by the Budkes in getting their bees to the plains of Texas, and then to the almond groves of California, mirror those of virtually all beekeepers.