Municipal authorities in La Prairie say Mayor Lucie F. Roussel passed away in hospital on Sunday.
A spokeswoman for the town said Roussel, 51, was not allergic to wasp stings.
"She was stung on several parts of her legs — about 15 times from what we think," Chantal Charron said Monday.
"She was overcome by the number of stings. When the ambulance technicians arrived, they tried to give her (an adrenalin injection) but they couldn't save her."
Jean Bergeron, the town's director-general, said he was in a "state of shock."
"Losing someone in such a way is difficult," he said. "It's traumatic."
Roussel, who was stung while gardening at her cottage in Stratford, about 200 kilometres east of Montreal, ran unsuccessfully for the Quebec Liberals in the 2012 provincial election.
Flags on municipal buildings in La Prairie, just south of Montreal, flew at half-mast on Monday.
Roussel had two adult children: Constance, 18, and Antonin, 19.
"She was a dynamic woman," said Suzanne Roy, head of the union of Quebec municipalities.
"She was in politics because she believed in families and believed she could bring about change."
Premier Philippe Couillard also tweeted his condolences.