Green spruce-larch adelgid

Systematic position: The green spruce-larch adelgid (Sacchiphantes viridis) belongs to the order Hemiptera and the family Adelgidae. These insects are specialized plant-sucking pests that have evolved to live exclusively on coniferous trees, causing significant physiological stress to their hosts.

Affected plants: The primary hosts for this species are Norway spruce and European larch. The insect requires both tree species to complete its complex, multi-year lifecycle, making stands where these two species grow together particularly susceptible to infestation.

Biology and lifecycle: The lifecycle of the adelgid spans two years. During spring, nymphs on spruce induce the growth of green, pineapple-shaped galls. Inside these galls, the insects mature. Eventually, winged forms migrate to larch needles, where they feed and reproduce. Later generations return to spruce to overwinter and restart the cycle.

Damage and economic impact: On spruce, the most recognizable sign of damage is the presence of green, cone-like galls on shoots, which cause stunted growth and needle yellowing. On larch, the infestation manifests as white, fluffy wax secretions on the needles, leading to chlorosis, needle drop, and overall reduction in tree vigor.

• Manual removal and destruction of fresh green galls on spruce before they open.
• Application of systemic insecticides during migration phases in spring and late summer.
• Dormant oil sprays applied in early spring to target overwintering nymphs on bark crevices.
• Maintaining tree health through proper irrigation and soil care to improve natural resistance.