Currant stem girdler

Janus integer, commonly known as the currant stem girdler, is a species of sawfly belonging to the family Cephidae (stem sawflies). This insect is a significant pest in both agricultural and horticultural settings, specifically targeting woody plant tissues.

The primary host plants for this pest include black currant, as well as several willow and poplar species. The damage is exclusively caused by the larvae, which bore into the stems, feeding on the central pith and disrupting the vascular system of the shoots.

The biological cycle begins in the spring, coinciding with the flowering of currant bushes. The female adult uses its ovipositor to make a circular incision around the shoot, depositing an egg. Upon hatching, the larva creates a downward tunnel inside the stem, consuming the pith as it grows.

The characteristic sign of an infestation is the sudden wilting and drooping of the shoot tips in late spring or early summer. A close inspection of the damaged area will reveal a distinct girdling mark on the stem surface, which is a clear diagnostic feature for this specific pest.

Effective management strategies focus on sanitation and chemical intervention. Growers should prune and destroy all wilted shoots, ensuring the cut is made below the larval tunnel to prevent the insect from emerging. Additionally, applying registered insecticides during the adult flight period can significantly reduce infestation levels.