Ash sawfly

Taxonomic position: The ash sawfly (Tomostethus multicinctus) belongs to the order Hymenoptera and the family Tenthredinidae. It is a specific pest that targets trees of the genus Fraxinus, causing significant defoliation in both urban and forest ecosystems.

Host plants: The primary host for this species is the ash tree (Fraxinus). The pest is most commonly found in habitats where these trees are prevalent, including public parks, forest stands, and ornamental landscape gardens.

Biology and life cycle: The adult sawflies emerge in the spring, coinciding with the bud break of the host trees. Females lay eggs directly into the leaf tissue. The larvae, often referred to as false caterpillars, feed on the foliage for several weeks before descending to the soil to pupate and overwinter in a cocoon.

Damage and economic impact: The larvae cause severe damage by skeletonizing leaves, consuming the leaf tissue between the veins. In cases of heavy infestation, the entire tree can be defoliated. This loss of foliage reduces the tree's ability to store energy, leading to stunted growth, dieback, and increased susceptibility to secondary infections.

Management strategies: Controlling the ash sawfly involves both cultural and chemical methods. Cultural practices, such as cultivating the soil beneath the canopy in late summer or autumn, can help destroy the pupae. During larval feeding, application of approved insecticides is recommended to prevent extensive damage. Maintaining tree vigor through proper irrigation and fertilization is also crucial for recovery.