How 12 Wasp Stings Triggered a Backcountry Helicopter Rescue

Outside Associate Editor Madison Dapcevich spoke with the responding search-and-rescue agency to debunk rumors about the number of stings and understand how backcountry visitors can protect themselves against wasp stings.

A routine climb in British Columbia, Canada, quickly turned into an emergency when a 33-year-old woman was stung more than a dozen times by wasps on August 25.

The woman, whose name has not been released, and her climbing partner were descending Redoubt Wall, a popular rock climbing area about 20 miles south of Vancouver. Given the number of stings and the potential for a serious systemic reaction, Lions Bay Search and Rescue (LBSAR) deployed a ground team carrying emergency medical equipment, including epinephrine, officials wrote in a statement.

“She was experiencing a full systemic allergic reaction with hives all over her body. She was dizzy, had some difficulty breathing, and had low blood pressure,” Maria Masiar, LBSAR search manager, told Outside

Initial information provided through 911 indicated that the woman, who is an experienced climber, had been stung more than 100 times, but Masiar said she likely suffered between 12 and 20 stings.

“But after assessing the subject, we believe that number was an overestimate,” Masiar said. “Regardless of the number of actual stings, the important issue was the systemic reaction of that much venom.”

North Shore Rescue helicopter crews and advanced medical providers hoisted the woman from the mountain and transferred her to an ambulance for further care, responding agencies wrote in a statement.

It’s an Unusually Bad Year for Wasp Activity

Even a handful of wasp stings can quickly escalate into a backcountry emergency. People with allergies may experience anaphylaxis, which can cause difficulty breathing, swelling of the lips, tongue, or throat, and dizziness or fainting. Mild stings can cause uncomfortable pain, swelling, and itching. Carrying an EpiPen, antihistamines, and an emergency satellite device can help in a serious situation.

This year has been particularly bad for wasps in the area, Masiar said. Yellowjackets in southern B.C. nest in the ground, often hiding their colonies beneath roots, rocks, logs, or other vegetation near trails. A person may not see the nest until they accidentally step on or near it, inciting dozens of wasps to defend their colony, LBSAR wrote in a blog post. Unlike bees, wasps can sting repeatedly.

“Interestingly, a second climbing party descended through the same area about an hour later and was also stung by the same wasps—approximately 20 times,” Masiar said. “Fortunately, they did not develop a systemic reaction and were able to hike out on their own.

By August and September, a single colony can contain hundreds or thousands of guardian wasps all protecting their home.

“Wasp activity can remain significant into late summer and early fall,” Masiar said. “Colonies are at their largest at this time of year, and wasps can become increasingly active as their usual food sources begin to diminish. This year, getting stung 10 to 20 times is NOT unusual.”

Their abundance is in part due to a relatively mild winter followed by an early, warm spring. More queen yellowjackets were able to survive hibernation and establish new colonies, expanding their colonies by late summer.

LBSAR tracks wasp nests across British Columbia and asks people to report sightings to its database.