Ash sawfly

Taxonomic position. Tomostethus sinofraxini belongs to the order Hymenoptera, family Tenthredinidae (common sawflies). It is a specialized pest species known for its specific host plant association within the genus Fraxinus (ash trees).

Host plants. The primary hosts for this insect are various species of ash trees. The pest is frequently encountered in forest ecosystems, urban landscaping, and shelterbelts where ash trees are present, posing a threat to both young stands and mature trees.

Biology and life cycle. The life cycle is synchronized with the phenology of the ash tree. Adults emerge in spring when buds begin to open. Females deposit eggs into the leaf tissue. Larvae feed on leaves throughout the spring and early summer. After completing their development, larvae descend to the soil for pupation and diapause.

Damage and economic impact. Larvae cause significant foliar damage by consuming leaf tissue, often leading to complete defoliation. Repeated defoliation events during growing seasons weaken the trees, making them susceptible to secondary pathogens, wood-boring insects, and environmental stress, ultimately leading to reduced timber quality or tree mortality.

Protection measures. Integrated pest management strategies include:

• monitoring larval populations using visual inspections and pheromone traps;
• enhancing natural biological control by preserving beneficial predator populations;
• applying biological insecticides, such as microbial agents, during the early larval stages;
• selective use of systemic insecticides in high-infestation areas to prevent severe tree stress and damage.