Birch sawfly

The birch sawfly (Trichiosoma lucorum) is a member of the Cimbicidae family within the order Hymenoptera. This insect is primarily recognized as a specialized defoliator that affects deciduous trees, with a geographical distribution covering much of the Palearctic region, particularly in woodland and urban garden environments.

The primary host plants for this species are birch trees (genus Betula), although the larvae are occasionally observed on willows, alders, and poplars. The larvae are the stage responsible for the damage, as they possess chewing mouthparts capable of consuming significant amounts of foliage in a relatively short period.

The biological cycle of Trichiosoma lucorum consists of a single generation per year. The species overwinter as prepupae inside thick-walled, barrel-shaped cocoons attached to twigs or branches. Pupation occurs in the spring, followed by the emergence of adults who mate and oviposit into the leaf tissue of host trees.

The damage caused by the larvae is characterized by the consumption of leaf edges and subsequent skeletonization of the foliage. Heavy infestations can lead to severe defoliation of the trees. While a healthy birch tree can usually recover from a single year of defoliation, repeated attacks over several seasons significantly reduce tree vigor and increase susceptibility to other stressors.

Effective management strategies should focus on integrated pest management (IPM) practices. During the winter months, manually removing and destroying the cocoons found on branches is a highly effective non-chemical control measure. For severe outbreaks, horticultural oils or registered insecticides targeting young larvae are recommended during the early larval development stage to minimize foliage loss.