Almond seed wasp

The almond seed wasp (Eurytoma amygdali) is a member of the order Hymenoptera and the family Eurytomidae. It is considered a serious economic pest, particularly in the Mediterranean basin and other regions where almond cultivation is prominent, as it directly attacks the seed within the fruit.

This species exclusively infests the fruit of the almond tree (Prunus dulcis). By targeting the developing kernel, the larvae ensure the destruction of the reproductive part of the fruit, leading to substantial yield losses that can significantly affect the commercial viability of an orchard.

The life cycle of the almond seed wasp is univoltine, meaning it has one generation per year. Larvae overwinter inside infested, shriveled almonds, either hanging on the trees or on the orchard floor. In the spring, when the almonds begin to set, the adults emerge, mate, and the females use their ovipositors to insert eggs into the soft shell of the young green fruit.

Damage symptoms are often delayed until harvest. Infested fruits appear smaller, lighter, and often remain on the tree throughout the winter, turning gray or brown. A small round exit hole on the almond hull indicates that the adult wasp has already emerged, leaving behind a hollow, empty shell where the kernel once was.

Control strategies for Eurytoma amygdali require strict orchard hygiene. Farmers are advised to remove and destroy all infested fruits from both the trees and the ground before the spring emergence period. Chemical control is limited to precise timing, applying systemic or contact insecticides just as the adult wasps emerge, to prevent egg-laying before the shell hardens.