Plum sawfly

Taxonomic classification: The plum sawfly (Hoplocampa minuta) is a member of the Hymenoptera order, specifically within the Tenthredinidae family. It is a significant pest of stone fruit, known for causing extensive economic losses in European and regional plum-growing areas.

Host plants and damage: The primary host is the plum tree, although it can also infest damsons, gages, and occasionally apricots. The larvae are the damaging stage; they burrow into young fruitlets, feeding on the developing kernel and pulp. A single larva can destroy multiple fruits, leading to heavy premature fruit drop.

Biology and lifecycle: The species overwinters as a mature larva inside a silk cocoon within the soil. Pupation occurs in early spring, synchronized with the host tree's flowering period. Adult sawflies emerge and lay eggs within the sepals of blossoms. Upon hatching, the larvae immediately tunnel into the ovary of the fruitlet to begin feeding.

Signs of infestation: Infested fruits often show a characteristic small hole with a droplet of resin or gum exuding from it. Inside, the larva consumes the interior, leaving behind a cavity filled with black excrement. As a result, the damaged fruit typically turns dark and falls to the ground before maturity.

Control measures: Managing Hoplocampa minuta requires a mix of cultural and chemical interventions:

• Cultivating the soil beneath the trees in autumn to expose larvae in cocoons to predators and frost.
• Using sticky traps (white or yellow) to monitor or reduce adult populations during the flowering stage.
• Applying systemic or contact insecticides shortly after petal fall or pre-blossom, depending on local regulations.
• Promptly collecting and destroying fallen fruit to interrupt the pest's development cycle.