Poplar sawfly

Systematic position: the poplar sawfly (Trichiocampus viminalis) is a member of the Hymenoptera order, specifically the Tenthredinidae family. It is recognized as a significant defoliator, primarily impacting specific deciduous trees across various temperate regions.

Host plants and damage: this pest mainly targets willow (Salix) and poplar (Populus) species. The larvae are voracious feeders that consume leaf tissue, often starting with the underside of the leaf and progressing to complete skeletonization. Severe infestations can lead to premature leaf drop, stunted tree growth, and increased susceptibility to secondary pathogens.

Biology and life cycle: the adult sawflies emerge in the spring to lay eggs directly into the leaf tissue. Upon hatching, the larvae (often called false caterpillars) feed gregariously, meaning they stay together in distinct clusters. This social feeding habit is a key behavioral trait throughout their development, ending in pupation, which typically occurs in the soil or protected crevices.

Control measures: management starts with monitoring for larval clusters during the late spring and early summer. Mechanical removal of infested leaves is often sufficient for small ornamental trees. For larger areas or heavy infestations, biological control agents such as Bacillus thuringiensis or systemic insecticides are recommended to stop the damage before significant foliage loss occurs.

• Regular tree inspection during late May and June.
• Encouraging natural predators like parasitic wasps and birds.
• Use of selective insecticides only when the damage threshold is exceeded.

Economic impact: while individual trees may survive light attacks, repeated annual defoliation significantly reduces the decorative value of ornamental poplars and the productivity of willow plantations. Integrating cultural practices, such as maintaining healthy, well-watered trees, helps increase the host plant's tolerance to defoliation pressure.