Willow sawfly

The willow sawfly (lat. Nematus salicis) belongs to the Hymenoptera order and the Tenthredinidae family. It is a specialized pest primarily affecting various willow species, causing significant ecological and economic impact in forest plantations, nurseries, and urban ornamental plantings.

This insect primarily targets plants within the Salix genus. The larvae are voracious feeders, capable of stripping entire branches of their foliage. While they show a strong preference for willow trees, they can occasionally be found on poplar species, representing a broader threat to salicaceous flora in diverse landscapes.

The biological cycle of the willow sawfly includes overwintering as a pupa within a cocoon, typically buried in the soil or leaf litter beneath the host tree. Adult sawflies emerge in the spring to mate and oviposit on the underside of leaves. The larvae hatch and undergo several instars, with the most damage occurring during the final stages of their development before pupation.

Damage symptoms are distinct and easy to identify. Early-stage larvae skeletonize leaves by feeding on the soft tissue between veins, while later instars consume entire leaf blades, often leaving only the main veins intact. Severe infestations result in extensive defoliation, which severely stresses the tree, inhibits growth, and increases susceptibility to secondary diseases and pests.

Effective control strategies require an integrated approach. Cultural practices include tilling the soil under affected trees in late autumn to destroy overwintering cocoons and manually removing larval clusters in small-scale settings. Chemical control, involving specific insecticides, should be timed with the larval emergence phase to ensure maximum efficacy while minimizing the impact on beneficial predator insects.