Fir shoot sawfly

Systematic position. Pleroneura brunneicornis belongs to the order Hymenoptera and the family Xyelidae. This species is a specialized pest known for targeting specific coniferous tree species, particularly causing concern in forest nurseries and ornamental plantations.

Host plants. The primary host for this insect is the fir tree (Abies). It specifically attacks the succulent new shoots during the early stages of spring growth, which are crucial for the development of the tree's leader and lateral branches.

Biology and life cycle. The life cycle is tightly synchronized with the host plant's phenology. Adult sawflies emerge in the early spring as buds begin to burst. Eggs are deposited into the tissue of developing shoots, where larvae hatch and immediately begin feeding internally, consuming the soft tissues and pith.

Damage and economic impact. The infestation results in the yellowing, wilting, and subsequent death of the current year’s growth. Affected shoots typically bend, turn brown, and eventually break off. This damage can severely deform young trees, hindering their height growth and structural integrity.

• Sanitation pruning: removing and destroying infested shoots before larvae exit.
• Monitoring emergence patterns using yellow sticky traps or pheromone baits.
• Applying systemic insecticides during the peak of adult activity or early larval stages.
• Promoting healthy tree growth through proper irrigation and soil management to increase tolerance.