How to Identify and Treat Spider Mites in Spruce Trees
Are Your Spruce Trees Looking Sickly?
If the needles on your spruce tree are turning yellow, brown, or dull green — especially starting on the lower branches — you might be dealing with spider mites. These tiny pests are a common problem in southern Alberta, especially during hot, dry summers, and they can cause serious damage to your spruce trees if left untreated.
What Are Spider Mites?
Spider mites are microscopic arachnids that feed on the sap inside spruce needles. As they feed, they leave behind tiny punctures that cause needles to lose their color and vitality. Severe infestations can lead to heavy needle loss and long-term stress for the tree.
One of the most common culprits in spruce trees is the two-spotted spider mite, but other species may also be present depending on the season.
Why Spruce Trees Are Vulnerable
Spruce trees — especially Colorado blue spruce — are highly susceptible to spider mites because of their dense needle structure and sensitivity to drought stress. Mites thrive in hot, dusty conditions, which are common in Lethbridge and surrounding areas during the summer.
Signs of Spider Mites in Spruce Trees
Here’s what to look for:
Fine, silky webbing on needles and twigs (especially in the inner branches)
Speckled, yellowing, or bronzing needles
Browning starting at the base of the tree and moving upward
A dusty appearance on the foliage
Premature needle drop
Tiny moving dots on the underside of needles (a magnifying glass or white paper test can help)
The White Paper Test
To confirm a spider mite infestation, try this simple test:
Shake a spruce branch over a sheet of white paper. If you see tiny specks that begin to move — usually red, brown, or greenish in color — you’ve likely got spider mites.
How We Treat Spider Mites in Spruce
At Timberline Arborists, we use professional-grade insecticides to control spider mites effectively and safely. Here’s our typical treatment process:
A thorough site inspection to assess mite activity and tree health
Targeted spraying using a properly calibrated high-pressure sprayer
Advice on watering, mulching, and stress reduction for long-term tree health
Follow-up visits if necessary to monitor population rebound
Timing is key: we typically spray during late spring and summer, when mite activity is highest. Treating early, before populations explode, yields the best results.
Can You Prevent Spider Mites?
Yes — while you can’t guarantee you’ll never get them, you can reduce the risk significantly:
Water deeply during dry spells (mites love drought-stressed trees)
Mulch around the base to retain moisture and keep root zones cool
Avoid over-pruning, which stresses the tree and removes natural shade
Schedule regular inspections to catch problems early
Worried About Spider Mites in Your Spruce?
If you suspect spider mites are damaging your spruce trees, don’t wait until it’s too late. Contact Timberline Arborists for a professional diagnosis and treatment plan. We’ll help restore your trees’ health and protect them from further damage.
Internal Link Suggestion:
“Looking for a long-term approach to tree health? Explore our Plant Health Care Services to learn how we can help.”
