European apple sawfly

The European apple sawfly (Hoplocampa testudinea) is a significant pest of apple trees, belonging to the order Hymenoptera, family Tenthredinidae. This insect is highly specialized and poses a serious threat to the fruit production of domestic apple orchards by attacking the developing flowers and fruitlets.

The life cycle of the sawfly is strictly synchronized with the phenology of the apple tree. The pest overwinters as a mature larva in a cocoon deep within the soil. Adult sawflies emerge during the bloom period, at which time they mate and lay eggs into the base of the blossoms, specifically within the calyx tissues.

The larval stage causes the most damage. Upon hatching, the larva bores into the young fruitlet, often leaving a distinctive spiral scar on the skin before consuming the seeds and the core. During its development, a single larva can migrate and destroy multiple fruitlets, leading to widespread premature fruit drop.

Infested apples that remain on the tree develop deep, corky, ribbon-like scars, which render them unmarketable. It is important to note that this pest is strictly host-specific to apple trees. It does not attack unrelated crops such as sugar beet, rapeseed, cabbage, peppers, sunflower, barley, or hops, which are commonly grown in adjacent fields.

Effective control strategies focus on both cultural and chemical interventions. Cultural methods include cultivating the soil beneath the canopy in autumn to expose overwintering larvae to predators and environmental stress. Chemical control must be timed precisely; it is most effective immediately after petal fall, before the larvae burrow deep into the fruitlets.

• Application of registered systemic or contact insecticides.
• Monitoring adult population levels with white sticky traps.
• Removal and destruction of fallen, infested fruit.
• Soil cultivation around the base of trees in autumn.