Hawthorn sawfly

The hawthorn sawfly (Trichiosoma tibiale) belongs to the order Hymenoptera and the family Cimbicidae. It is a distinctive insect known for its robust size and its larval stage, which feeds on the foliage of various woody plants, often causing localized defoliation in orchard and park environments.

The host range of this pest primarily includes members of the Rosaceae family. It is most frequently encountered on hawthorn, willow, alder, and common orchard species like apple, pear, and cherry trees. The larvae are voracious feeders, capable of stripping branches of their leaves during high-density infestations.

The biological cycle involves wintering as a prepupa within a tough, parchment-like cocoon attached to host plant twigs. Adults emerge in spring to mate and lay eggs. The female inserts her eggs into leaf tissues, ensuring that the emerging larvae have immediate access to food sources as they progress through several developmental instars.

Damage caused by the larvae is characterized by the consumption of leaf blades. Younger larvae often skeletonize leaves, while older stages consume entire leaf areas, leaving only the primary veins. This significant reduction in foliage impairs the tree's photosynthetic capability, resulting in reduced vigor, poor shoot development, and yield loss.

Effective management requires an integrated approach. Cultural practices such as winter pruning and the destruction of cocoons can significantly reduce the overwintering population. In cases of severe outbreaks, targeted applications of approved insecticides during the early larval stages are necessary to minimize damage and prevent tree stress.