European fruit scale

The European fruit scale (Diaspidiotus ostreaeformis) is a member of the Diaspididae family within the order Hemiptera. It is recognized as a significant pest of various fruit-bearing trees, known for its ability to rapidly colonize woody parts of host plants under favorable climate conditions.

This pest primarily attacks rosaceous plants, including apple, pear, plum, cherry, and peach trees. It can also infest various ornamental trees and shrubs such as linden and willow, allowing the pest to maintain high population levels even in mixed plantations and hedgerows.

The life cycle of the European fruit scale consists of one generation per year. The insect overwinters as a first-instar nymph (crawler) underneath its protective shield on the bark. As temperatures rise in spring, these nymphs resume feeding, mature into adults, and proceed to reproduce, with females depositing eggs under their scale covering.

The damage is caused by the nymphs and females sucking sap from the branches and trunks. This feeding activity weakens the tree significantly, results in bark cracking, inhibits shoot growth, and can cause twig dieback. Fruits affected by the scale often develop reddish discolorations, reducing their commercial value.

• Implementing regular pruning to improve air circulation and canopy penetration.
• Scrubbing the trunk and main branches to mechanically remove scale colonies.
• Applying dormant oil sprays in late winter or early spring to suffocate overwintering nymphs.
• Timing insecticide applications to coincide with the emergence of crawlers for maximum efficacy.