Rob Progar, an entomologist with the Pacific Northwest Research Station, is featured in this PBS video on a "Rare Snowstorm of Pine Butterflies," the largest recorded outbreak of pine butterflies in the Blue Mountains ever.

"It's spectacular," Progar said. "This event only happens every 30 years, 20 years. It's something that I feel fortunate to be part of. Next time it happens, I'll be retired and hopefully still alive."

Watch the video below.