A Manitoba family is stunned and seeking answers after a swarm of wasps killed a man in a southwestern town earlier this week.

Lloyd Mason, 63, was cutting wood outside his house in Baldur, Man., on Monday when he was swarmed and stung repeatedly by wasps.

He stumbled into his house, where his wife Shirley gave him an antihistamine and performed CPR while waiting for an ambulance.

"He was able to talk to Shirley and tell what happened, but he very quickly collapsed," Scott Wood, Mason's son-in-law, told CBC News. "He just didn't make it."

The medical examiner told the family it appears Mason died from a severe allergic reaction to the multiple stings, Wood said.

"Lloyd was a very active, outdoors person," Wood said. "It's such a shock that something that seems so simple could cause this."

Death 'a shock'

Wasps are common in the area, about 160 kilometres southwest of Winnipeg, but they seem different this year, he added.

"This summer they seem a little more aggressive," he said. "I was stung just a week ago out here, literally sitting in a chair, one crawled up on my hand and bit me."

After the medical examiner's office suggested an entomologist might have a closer look at the insects, the family is attempting to trap some of the wasps, Wood said.

"We'd like to know a little bit more," he said. "If it is just the typical, ordinary wasp and it was the number of stings, it's something you can watch out for. If it's a different type of wasp, then you maybe have to take more precautions."

More aggressive wasps

Wasps are common in rural and urban areas around North America. The most aggressive species typically seen in Canada is the German yellow jacket, which is often seen scavenging in city garbage, according to Health Canada.

Over the past 10 to 15 years, Manitoba has seen an increase in the number of German yellow jackets, the type that likely stung Mason, University of Manitoba entomologist Rob Currie said Friday.

"It's probably a yellow jacket, and there's probably a high probability it's that particular wasp," he said, adding that the late fall is the worst time of year in Manitoba for wasps.

"This is the time of year when wasps do tend to get more aggressive because their natural food sources are drying up, and as a result of that they tend to be a little more aggressive when they're foraging."

"They also tend to be in larger colonies [in the fall], so if you happen to disturb a nest, there's many more individuals in there that come out and guard the nest and defend it."

'Very potent' venom

Mason had been stung by wasps before and had not shown an allergeic reaction, Wood said.

But Currie says not reacting to past stings doesn't mean a person is not allergic. Past stings can often bring on an allergy, he said.

"Usually the way the allergic reaction works in response to stings is that you have to be stung at least once before you start to develop a severe allergic reaction and it's usually on subsequent stings that you're going to eventually have a severe allergic reaction."

Wasps release a "very potent" venom when they sting, and severe allergic reactions to the venom can kill a person, according to Health Canada.

Antivenin shots can help prevent severe reactions, so anyone who has been stung and is experiencing symptoms of anaphylactic shock — such as faintness, flushing in the face, rapid heartbeat, difficulty breathing, or redness, swelling or itchiness of face, mouth or throat — should seek immediate medical help.

If no allergic reaction occurs, Health Canada recommends soothing stings with ice packs or a baking-soda paste.