Green spruce aphid

Systematic position: The green spruce aphid (Elatobium abietinum) belongs to the order Hemiptera and the family Aphididae. It is a specialized pest that is highly adapted to feeding on specific coniferous hosts, causing significant physiological stress to trees.

Host plants: The primary hosts for this species are members of the Picea genus. It is particularly notorious for damaging Norway spruce (Picea abies) and Sitka spruce (Picea sitchensis), though it can infest various other spruce species in urban and forest environments.

Biology and life cycle: This aphid species is notable for its ability to survive mild winters in an active state. Population growth typically begins in late winter or early spring as temperatures rise. Because they reproduce parthenogenetically, the population can explode rapidly during cool, damp spring weather, leading to heavy infestations before natural predators become fully active.

Damage and severity: Aphids pierce the needles and feed on the sap, causing needle yellowing, necrosis, and premature needle cast. The damage is usually most severe on older needles within the lower and inner canopy. Sustained infestation results in thinning crowns, reduced tree growth, and increased susceptibility to secondary infections or environmental stress.

Control measures: Effective management relies on early detection and integrated pest management practices:

• Application of systemic or contact insecticides during early spring before needle drop.
• Encouraging natural biological control agents such as ladybirds, lacewings, and hoverflies.
• Using high-pressure water jets to wash aphids off the foliage in smaller garden settings.
• Maintaining tree vigor through proper site selection, irrigation, and fertilization to help trees recover from feeding damage.