Spruce sawfly Sharliphora nigella

Systematic position. The insect belongs to the order Hymenoptera, specifically the family Tenthredinidae (common sawflies). Sharliphora nigella is a specialized pest that has evolved to feed exclusively or primarily on coniferous host plants, making it a significant concern for silviculture.

Host plants and damage type. The primary hosts are trees of the genus Picea (spruce). The larvae are known as false caterpillars; they feed on spruce needles, consuming them entirely or partially. This feeding behavior causes significant defoliation, which severely reduces the tree's ability to perform photosynthesis and maintain its vigor.

Biology and life cycle. The life cycle involves complete metamorphosis: egg, larva, pupa, and adult. Females lay eggs inside the needles using their saw-like ovipositor. The larvae emerge and undergo several instars while feeding. The species typically overwinters in a cocoon buried within the forest soil or leaf litter, protected from extreme temperatures.

Economic impact. Infestations by Sharliphora nigella can result in severe needle loss, leading to the thinning of tree crowns. Persistent damage weakens the host tree, making it susceptible to secondary infestations by bark beetles or wood-boring insects, ultimately leading to the decline or mortality of mature spruce stands and nursery saplings.

Protection measures. Effective control requires an integrated approach to manage the population levels:

• Regular monitoring of adult activity using pheromone or sticky traps.
• Application of biological insecticides containing specific viral strains or bacteria (e.g., Bt).
• Chemical treatments applied during the early larval development stages to minimize impact.
• Silvicultural practices that promote high biodiversity to encourage natural predators, such as birds and parasitic wasps.