This depends on the type and severity of the infestation. Generally speaking, an infestation is only considered to be controlled once the last surviving moths have laid their eggs. Once these are then parasitised by the parasitic wasps, there will be no new generation of moths. When it comes to a pantry moth infestation, it will take about 8 weeks to be moth-free again. This corresponds to approximately 2 weeks after the fourth and final delivery, provided you have used the beneficial insects correctly and continuously.