Spruce leafroller

The spruce leafroller (lat. Epinotia fortunana) belongs to the family Tortricidae, order Lepidoptera. This is a specialized pest primarily found in coniferous stands, specifically targeting spruce trees. Despite the small size of the adult moths, the larvae are capable of causing significant damage to both ornamental and forestry spruce populations.

The main host plants affected by this insect are various species of spruce (Picea spp.). It is the larvae that cause the damage, actively feeding on the needles and tender tissues of young shoots during their developmental stages. High population density of the pest can lead to severe weakening of the trees, loss of aesthetic value, and a reduction in annual growth rates.

The biology of this pest is closely linked to the phenology of spruce growth. Adult moths are typically active during the summer months. After mating, the females lay eggs on the needles or bud scales. The emerging larvae undergo several instars and eventually pupate directly on the tree, often within silken webs between needles or inside bark crevices.

Damage symptoms include the yellowing and subsequent shedding of needles, which are often found matted together with thin, silky webbing. Larvae consume the internal tissues of the needles, creating characteristic mines or hollowing them out completely. Accumulations of frass held together by webbing are a tell-tale sign of an infestation, making identification easier during visual inspections.

Effective management of the spruce leafroller requires a combination of cultural and chemical strategies. Regular monitoring of the foliage during the growing season is essential for early detection. If a major infestation occurs, treatments with systemic or contact-stomach insecticides approved for use on conifers are highly effective. Additionally, maintaining overall tree vigor through proper watering and fertilization helps the trees withstand pest pressure.

• Insecticide spraying during the peak larval emergence period.
• Sanitary pruning of heavily infested shoots.
• Encouraging natural predators such as birds and beneficial insects.