Fly nut belongs to the family Tephritidae. Adult has between 4 and 8 mm, similar to the house fly. The female lays eggs on the fruit, in groups, in a cavity excavated on the green and tender skin. Hatch within 5 days. The larvae develop and feed on the tender bark that turns white and stringy and then turns black. Generally the first adults appear on July until October. Acquire maturity between 3 and 5 weeks later, drop to the ground where they remain in the pupal stage until the following year. The attack can be mistaken for fungal attack if we look once the larvae have left the fruit. It is American origin and emerging Europe. In heavily attacked trees and untreated can lead to loss of 80% of the crop.

In general, early varieties of walnut are more sensitive. Control is difficult. In principle it is necessary to place traps for adults and determine the time of surgery. It is yellow plates with adhesive, the adults attracted by the color stick.

Chemical control can be carried out: thiacloprid (Calypso), Spinossrad (Succes-4), phosmet (Imidan) or pyrethroids, depending on product authorizations.