Colorado’s lodgepole pines beset with a burgeoning bug infestation |

Colorado’s lodgepole pines beset with a burgeoning bug infestation

Breeana Laughlin
Submitted photo/John A. Weidhass

A tiny, unassuming Colorado insect has been spotted making a big mark on lodgepole pines.

Foresters are finding that the insect, called pine needle scale, has been causing lodgepoles to appear sickly, with yellowing or fading needles.

While it’s normal to see pine needle scale occurring naturally in the woods, this year foresters are seeing entire areas where infestations are impacting the health and vigor of trees.

“To be honest, we aren’t 100 percent certain why the populations have increased so dramatically,” said Ryan McNertney, a forester with the Colorado State Forest Service Granby District.

The Colorado State Forest Service has gotten calls from concerned Grand County homeowners, who’ve described their trees as a turning a dingy green or yellow color.

McNertney said he’s hasn’t heard about the phenomenon occurring Summit County yet, but whatever is causing the spike in population could have the potential to occur in our community as well.

“Generally scale outbreaks occur in isolated areas with a quick influx in populations and then die off,” McNertney said. “But we have seen so much this summer that we wanted to inform the public about what was going on.”

Pine needle scales are in a different category of insects than the pine beetle that has wreaked havoc on lodgepole pines in Colorado.

The pine needle scale is part of a group of insects with specialized mouthparts, similar to a tube, used to suck moisture and nutrients from tree tissues. The tiny and largely immobile pine needle scale feeds on the needles of most species of pines, spruce and fir. Infestations can be spotted by the presence of a number of hard, white spots dotting the needles of invaded trees.

Cold weather and predatory insects, such as lady beetles, typically keep the pine needle scale in check. But recent infestations are setting new precedents for the species.

William M. Ciesla, of Forest Health Management International, is familiar with pine needle scale in Colorado through his contract work on federal lands.

Ciesla said he hadn’t heard of the outbreak of insects in Grand County, but said he recently encountered an infestation of pine needle scale in and around Rustic, Colo., in the Cache la Poudre River Basin, where similar damage is occurring in blue spruce.

“There were places were you’d see seven or eight scales on an individual spruce needle. It was a pretty heavy infestation,” Ciesla said. “What I saw up in Rustic was unusual. It’s interesting that it is showing up in another place.”

There is little landowners can do to combat these insect pests, especially after they have formed their protective white scales. McNertney said some landowners may opt to use horticultural oils and insecticidal soaps to kill pine needle scale, but said they may only dry out the trees and cause more damage.

McNertney said he’s seen an increase in the amount of bugs — and the damage they cause — in recent years, with the most notable spike occurring this year. Unfortunately, with few ways to combat the bug, and without knowing what’s causing the population spike, it’s a game of “wait and see,” he said.

“I don’t think we will see this continue for very long, but it’s hard to tell because we’ve seen such an increase in populations over the last couple of years.”

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