Raspberry sawfly

The raspberry sawfly (Priophorus tristis) is an insect species belonging to the order Hymenoptera and the family Tenthredinidae. Adult sawflies are small, dark-colored insects that are often overlooked by gardeners during the early stages of their activity in the spring.

The host plants for this pest primarily include raspberry and blackberry species. It is the larval stage (false caterpillars) that is responsible for causing significant damage. These larvae feed on the foliage, often congregating on the undersides of the leaves to consume the tissue between the veins, leading to significant defoliation if left unchecked.

The life cycle of Priophorus tristis involves multiple generations within a single growing season. Females lay their eggs into the leaf tissue, and after hatching, the larvae go through several instars of intense feeding. Once mature, they descend to the soil, where they spin cocoons to pupate and overwinter, completing their transformation.

Damage assessment is based on the presence of leaf skeletonization. When larvae are numerous, they can strip entire leaves, leaving only the primary veins behind. This stress reduces the plant's ability to photosynthesize, resulting in weakened canes, reduced vigor, and a noticeable drop in berry yield for the current and subsequent harvests.

Management and control strategies focus on both cultural and chemical interventions. Tilling or disturbing the soil around the base of the bushes in late autumn or early spring can destroy overwintering cocoons. If infestation levels exceed the economic threshold, application of approved contact insecticides or biological control agents during the larval stage is highly recommended.

• Manual removal of damaged leaves where larvae are present.
• Soil cultivation around berry canes to disrupt life cycle.
• Encouraging natural predators such as parasitic wasps.
• Timely application of pesticides before fruit ripening.