Bees buzz atop a cargo van on a New Brunswick highway on Monday, June 30. (CBC-TV)

Improving weather conditions in northwestern New Brunswick is making the recovery of 12 million bees that spilled onto the Trans-Canada Highway after an accident on Monday morning more difficult.

Until the late afternoon, light rain in the area had kept most of the honeybees calm as bee experts worked to slowly move 330 crates of the insects onto a new truck after the vehicle they were in overturned.

But as the weather lifted in the afternoon, the bees began to swarm and sting the workers more, police said.

Officials are now smoking the bees and using hoses from fire trucks to mist the crates, which contain about 35,000 bees each and four hives, in an attempt to calm them and make them more manageable to move.

Police set up a detour in the area to reroute traffic on Monday afternoon.

Initially the westbound lanes of the Trans-Canada Highway near the accident scene were closed but many locals were flocking to the area to see the accident, police said.

The bees are becoming agitated by all the activity around them and have begun flying, police said.

Just having some of the lanes of traffic closed was still posing a risk to the public because many of the people passing through the area were on motorcycles or in convertibles, police said.

Bees began to escape on Monday morning after the truck transporting them overturned on a Trans-Canada Highway ramp near Saint-Léonard in northwest New Brunswick after its load shifted, RCMP said. The driver was not injured.

The bees were being returned to a beekeeper in Ontario after being used to pollinate blueberry crops near Tracadie-Sheila in northeastern New Brunswick.

'They got nasty,' says beekeeper

Though only the crate in the front of the truck had been damaged in the accident, the work to move the insects seems to be encouraging more bees to leave the boxes, said Drummond beekeeper Edmond Bellefleur, who went to the site to have a look.

"Once they started to open the netting and [were] unpacking the hives one by one and putting them on pallets, then they really started to fly, and they got nasty," Bellefleur said.

There were enough bees in the area that their buzzing could be heard, CBC's Alison Northcott said.

She said the bees appeared to be swarming the people working at the scene. She said in the minute or so she spent outside of her vehicle, she was stung several times.

Seven bee experts arrived at the scene by about noon AT on Monday. Donning full beekeeper suits, they began the effort to move the bees and their crates to another vehicle to continue the journey back to Ontario, said RCMP Sgt. Derek Strong.

The bees will not be moved until nightfall, because they tend to return to their hives when it gets dark, he said.

No reason to panic

Strong said the experts onsite have reported the situation is under control and there is no reason for the public to panic.

However, anyone with bee allergies and at a risk of anaphylactic shock should leave the area until the situation has been resolved, Strong said.

Emergency personnel, including paramedics and ambulances, are on the scene in case anyone is stung, Strong said.

The detour on Monday was slowing traffic and backing it up for several kilometres. Officials said the highway is expected to be reduced to one lane until at least 9 p.m. AT.

Some stings have been reported by those at the scene, Strong said, but no injuries have yet been reported from the general public. The accident, however, is being treated as a public safety issue, he said.

Unlikely to survive on their own

Honeybees don't usually sting unless they are being bothered, said Richard Duplain, vice-president of the New Brunswick Beekeepers Association. The bees die after they sting someone.

If the bees are not captured, they could disperse into the countryside in search of a protected area, such as a tree hollow or a house, Duplan said.

He added that any of the bees that leave the truck aren't likely to survive for long after being raised by beekeepers.

"Weather conditions, birds and so forth would take a toll on the unprotected bees," Duplain said. "They don't create their own paper nest like wasps or hornets or bumblebees. They're pretty much at risk to the elements if they're not under the care and attention of an experienced beekeeper."

With files from the Canadian Press