KANPUR, June 19 -- Ravishankar Agarwal, a 70-year-old iron trader known for his punctuality and soft-spoken manner, stepped out of his car on an April morning in Kanpur for a morning walk.

As he fell a few steps behind his companions near the tree-lined flank of the Cantonment area, a furious swarm of bees descended without warning.

Agarwal, dressed in light cotton, fell to the road as stings multiplied. By the time he was rushed to the nearby military hospital, the man, who had weathered decades of business cycles and social change in Uttar Pradesh's industrial heartland, was declared dead.

Agarwal's death, though sudden, was part of a quiet, unsettling pattern that has emerged across India in recent months.

In just the last three mo...