Yep, those are Pandora moths flying around your front porch lights.
If they could speak, they'd be shouting, "We're baaaaaack!"
However, this has been a minor outbreak. Last time they appeared in massive numbers was in 1990 and '91. As you can see, they're attracted to lights—so if you don't want them to lay eggs on your pines, turn off your lights; you'll save energy and money at the same time.
The Pandora moth's life cycle works something like this: around the end of June, the adult moths appear (dig their way out of the ground where they went from caterpillar to adult in the pupae stage) and lay eggs, which hatch in August. Those larva satisfy their hunger by eating the needles of pines—and only pines. Pandora moths are not found everywhere. It's the loose pumice soils that make this part of North America their desired stomping (pardon, flying and eating) grounds. The pine tree needles (leaves) they devour go with the soils, making them a very specialized insect.
They grow as they eat, and at the point where they get too big for their britches, they burst the outer skin and the next instar (the term for growth of a caterpillar) emerges. After its 6th or 7th instar, the caterpillars leave the trees and bury themselves in the ground, where they will remain for a year (or, in some instances, two to four years) to later emerge as adult moths.
On a big hatch year, caterpillars heading for their underground home can cause—and have caused—costly problems for the Oregon Department of Transportation. During a massive outbreak in the '70s, cars and trucks on Highway 97 between Bend and Klamath Falls crushed millions of caterpillars attempting to cross the highway, which became slick as winter ice. As a result, sanding trucks had to be employed to prevent more accidents.
Kris Kristovich, retired Sisters cross-country coach, recalls back in '91 when he and his six-year-old granddaughter, Natasha, were attending a night baseball game in Vince Genna Stadium when the moths appeared in great numbers, making a real mess of things.
The earliest Pandora outbreak recorded was in 1893, when federal Indian Agents noticed the Klamath People roasting the larvae. Conversations with the Klamath leaders indicated the caterpillars were a wonderful addition to their diet when they appeared— which wasn't very often.
And here the moths are with us again... noticeably flying about the lights of homes, barns and businesses. The adult moths, however, have no interest in eating. Even if they did, they couldn't, as they have no eating apparatii. They're interested in one thing and one thing only: mating.
The female moths are flying about releasing pheromones (scent) that are distinctive to their species, which the males—with their oversized yellow antennae—are quick to sense and recognize. Nature, however, has dictated that they have only a very short time to get the job done; in about a week they'll all be dead.
The Paiute people of today in California's Owens Valley and Mono Lake areas still harvest, prepare, store and eat the larvae of the Pandora moth, which they call "piuga." The larvae are collected during their late August migration across the forest floor at the end of their first year of life. The caterpillars are gathered by hand once or twice a day and temporarily stored in trenches in the ground. The larvae are then roasted in fire-heated sand for 30 minutes; the sand not only cooks the insects but also serves to remove the fine hairs (setae) from their bodies.
Like other things in nature, everything is connected, and there are "natural controls" for population buildups. One is a "wilting virus" that puts the finish on expanding adult Pandora moth numbers. Also, during their population explosion, wasp and fly parasites lay eggs on, and in, the caterpillars, which also takes a great toll on the moths, while helping the wasps and flies to build up their populations.
Then there's our little Screech Owl look-alike, the Flammulated Owl. They nest in and around the Lava Top Butte area, south of Bend and in other pine forests with dead trees and woodpecker cavities. While most owls are rodent-eaters, flams, on the other hand, are insect-eaters, with Pandora moths high on their menu.
Sure, you can kill the moths with chemicals, but why bother? Nature's been dealing with insect outbreaks ever since the sun was a tiny thing, there weren't no moon and the Big Dipper was a little tin drinkin' cup. So, please, let them live out their time and you keep our air and soil clean of chemicals... this outbreak's about done anyway.