Oak slug sawfly

The oak slug sawfly (Caliroa annulipes) is a member of the Hymenoptera order and the Tenthredinidae family. Despite its common name, it frequently infests a wide range of broad-leaved trees, becoming a nuisance for forest nurseries, orchards, and urban park landscapes.

The list of host plants includes various species of lime (Tilia), oak (Quercus), birch (Betula), and beech (Fagus). In some instances, it may also attack fruit trees like cherries or pears, identifying these crops as ideal environments for larvae feeding and growth.

The biological cycle of this pest involves egg-laying within the leaf tissue, followed by the emergence of larvae. These larvae are slug-like in appearance due to a shiny, mucus-like coating that covers their backs, which provides protection from predators and desiccation during the day.

Damage is characterized by leaf skeletonizing, where the larvae feed on the leaf tissue between the veins. As a result, leaves appear as translucent webs of veins that eventually turn brown and fall off. This activity can cause severe stress to the trees, reducing their vigor over time.

Effective management strategies should focus on monitoring the population levels during the growing season.

• Application of contact insecticides during the larval stage.
• Soil cultivation around the base of trees to destroy overwintering cocoons.
• Encouraging natural predators such as parasitic wasps.
• Removing and destroying heavily infested leaves if the tree size allows.