A small, low-flying airplane that shook Aspenites out of bed early Tuesday morning was targeting pine trees on private property on Smuggler Mountain with bark pine beetle pheromones.

The plane flew over town around 6 a.m., en route to spray the trees.

The aerial treatment spreads flakes of verbenone over stands of pines. Verbenone is a beetle pheromone that, when applied to trees, can fool the insects into thinking a tree is already infested, causing them to back off. The chemical has been applied to trees on public lands on Smuggler in recent years for the same reason, but it was stapled to trees along trails, not spread from the air.

It is biodegradable, and not believed to be harmful to humans.

The private land treated in Tuesday’s flyover includes about 50 acres southeast of the public Smuggler land. Its owner couldn’t be confirmed Friday.

City of Aspen parks and open space director Stephen Ellsperman said he had been told in advance that the plane treatment would be used on the private holding this summer.

The flight was overseen by Bill Murray, a professor at San Jose State University specializing in forestry. He couldn’t be reached for comment on Friday, but he has worked with the local preservation group For the Forest — now part of the Aspen Center for Environmental Studies — to combat bark pine beetle infestation in the Aspen area.

The city of Aspen and Pitkin County began using verbenone on Smuggler in 2009, and some of the old packets are still up in the area. They haven’t used aerial treatments, and aren’t doing beetle mitigation work there this summer.

“We’re not seeing high levels of beetle activity,” said Ellsperman. “They’ve been on the decline over the last two years.”

The city and county had planned to remove beetle-kill trees from the area, along with a slate of forest health measures on Smuggler and in the Hunter Creek Valley this summer.

But the projects were called off earlier this summer, as extreme drought led to a local fire ban. It was to include extensive clearing of beetle brood trees and habitat projects that would require the use of chainsaws and hot equipment.

“With the fire danger it wasn’t worth it this year,” said Pitkin County land steward Gary Tennenbaum.

If recent rainfalls persist, the governments may spearhead some late summer or fall forest health projects in the area, both men said.

andrew@aspendailynews.com