Mountain Pine Beetle Allergies Afflict 32% in Affected Area

A tiny, voracious pest is not only cutting a wide swath of destruction through forests from British Columbia to New Mexico, it’s also harming people. Scientists have found that the mountain pine beetle — responsible for the death of millions of trees in the largest insect infestation ever in North America — has become a potential trigger for allergies in humans.


Until recently, the mountain pine beetle was a benign resident of the Western ecosystem — that is, until temperatures rose and made the climate suddenly more hospitable to the insects. As they flourished, they’d consume bark of pine trees in one region, then move on… and on. First the epidemic was reported in British Columbia, but now the beetles are responsible for millions of dead ponderosa and lodgepole pines in North America, including Montana, Wyoming and Colorado. The flying insects are migrating eastward by the billions, with some experts predicting the problem could travel all the way to the Great Lakes.

That’s bad enough — now these insects may also be bringing misery to humans. At an allergy clinic in a timber community in British Columbia, doctors became suspicious when patients complaining of itchy, watery eyes, sneezing, runny noses and nasal congestion began to test positive for cockroach allergies — in an area not known to have them. But airborne beetles were nearly ubiquitous at the time, and researchers found significant allergic cross-reactivity between cockroaches and mountain pine beetles. These results were presented at a March 2009 meeting of the American Academy of Allergy Asthma & Immunology.

Allergic reactions can occur when susceptible individuals inhale airborne proteins shed by insects such as cockroaches, dust mites, termites and — possibly — mountain pine beetles, explains Donald F. Stark, MD, clinical associate professor in the department of allergy & immunology at the University of British Columbia and former president of the Canadian Society of Allergy and Clinical Immunology. Dr. Stark discovered that 32% of patients tested at his clinic were reactive to pine beetle extract — a sign that they had developed allergies to the beetles. In contrast, only 7% of a comparable group of clinic patients showed signs of beetle-related allergies in Vancouver, a city in British Columbia unaffected by the infestation.


Dr. Stark cautions that there is still no firm proof that mountain pine beetles cause significant symptoms and further study is needed. In the meantime, if you live in an affected area and suffer from airborne allergies, you may want to get tested for this specific one. Use the following strategies to limit your exposure…

  • Keep windows and doors closed (especially during the early summer months) in areas known to have pine beetle infestation, particularly at night, when the pine beetles migrate.
  • Don’t use window or attic fans that draw in outside air.
  • Use air conditioning and choose the “recirculate” setting — both at home and in the car — to avoid introducing outside air that may contain airborne allergens.
  • Shower and change clothes following outdoor activities.

Dry clothes in a vented indoor dryer, not outside.