Scale insects strike Vail |

Scale insects strike Vail

Craig Keithley
Special to the Vail Daily
Vail, CO Colorado

VAIL, Colorado –While not as well known as the mountain pine beetle, scale insects have been infecting trees in Vail, Colorado at a greater rate in recent years and silently killing trees without much notice. The mountain pine beetle infestation results in the death of the tree the following year, while scale insects starve the plant they feed on over the course of several years, leading to a slow decline.

A property owner’s first awareness of the problem (and one that results in the most phone calls to our office) is the observation that their tree appears unhealthy and thin. Entire branches have died-back and the tree is dropping an unusual amount of needles or leaves.

A more thorough investigation exposes small, white specks against the green foliage. These are the sucking insects known as pine needle scale. There are several hundred species of scale active in the United States. In our region of Colorado most of our service calls are in response to pine needle scale, which attacks most evergreens but is typically found on spruce varieties.

There is also a scale insect active in our area that is found living camouflaged on the trunks of aspen trees: aspen scale. Its coloration, similar to that of the aspen trunk, makes it difficult to identify but its damage is similar to that of pine needle scale: a slow decline with no apparent reason.

Other components of a landscape, including shrubs, flowers and even houseplants, are prone to scale infestations. The result is always the same, as the plant eventually succumbs to starvation and slowly fades away.

There are a variety of treatment options available ranging from pesticide sprays, soil injections, trunk sprays and even direct trunk injections. There are synthetic pesticides, organic pesticides and even some bionatural control options.

All treatments have one thing in common: the scale insect must be treated in the proper stage of its life to result in effective control. This stage is known as the “crawler” stage and occurs right after hatching from their overwintering eggs.

The “crawlers” briefly leave the protective, waxy, scale covering and are quite vulnerable to control efforts. They seek out a location on the previous year’s growth to inject their sucking mouthparts and ingest juices. They will remain there for the rest of their lives. Once the insect begins covering itself with the white, waxy, scale covering, however, they are protected against all but systemic pesticides.

Here are some common questions and answers.

What should you do if you suspect scale insects are active in your landscape?

Call a professional. They have the knowledge and experience to offer environmentally sound control options.

Where have scale insects been seen locally?

Pine needle scale is approaching epidemic levels in Vail. There is an endless supply of spruce trees in Vail, which assist the scales’ ability to proliferate. Spruces are being skeletonized by the insect and many property owners don’t realize there’s a problem until it’s too late.

Aspen scale has been seen in Vail and moving westwards towards Gypsum. With its natural grey coloring, property owners have no reason to suspect an insect infestation.

Should I be concerned about scale?

Yes. Left untreated it doesn’t go away on its own and its activity always ends poorly for the tree.

Craig Keithley is the customer service manager and a horticulturist at Land Designs by Ellison/A Cut Above Forestry. For more information call 970-453-9154 or e-mail

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