A. Let me get rid of that first – I’ve never been a fan of those fake snowy Christmas trees. But that’s an interesting and accurate way of describing what you’ve observed. It’s pine needle scale, or PNS, an insect. Chionaspis pinifolia is native to North America but is fortunately a small pest in natural forests. The insect feeds on stinging / sucking mouthparts that extract nutrients from the tree needles and cause them to turn yellow. Fortunately, severe infestation is not common, but when combined with other plant stressors, the severity can lead to branch death and eventually small tree death.
