In interviews with CBC Radio Kitchener, beekeepers said up to 90 per cent of the province’s hives were wiped out.
Bernie Wiehle, president of the Ontario Beekeepers' Association, said fruit growers may be in trouble because there won’t be bees to pollinate blossoms.
Verroa mites feed on bees' blood and protein reserves, and can spread viruses among bees and weaken their immune responses, Paul Kelly, research and apiary manager at the University of Guelph Honey Bee Research Centre, told CBC.
Last year, spring came early, Kelly said, which was good for bees — but also favourable for the varroa mites, which were able to start reproducing early.
"The earlier the spring is, the more reproductive cycles these mites can go through," Kelly said. "It's like exponential growth."
Dennis Schmidt, who typically keeps between 20 and 30 colonies at a Waterloo apiary, said all but one have been wiped out this year.
"I have heard stories of beekeepers weeping when they finally open their hives and they find that their livestock have perished over the winter," said Schmidt, who is also president of the Wellington County Beekeepers' Association.
Kelly hopes further research on varroa mites and honey bees will yield solutions to keep the problem under control. The centre is also testing the use of essential oils and organic acids to kill the mites without harming the bees, he said.
Wiehle said there is so much demand to buy bees that there’s a shortage..
"They're just not available, and they're outrageously expensive — the price has probably doubled,” he said.
Wiehle hopes to meet with Lisa Thompson, the minister of agriculture, food and rural affairs of Ontario, to discuss financial relief for commercial beekeepers hit hard by the varroa mite.
In response to a request from CBC, a spokesperson for Thompson said the minister's office is working to schedule a meeting soon.