The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important pest of fresh horticultural produce and as such is considered a biosecurity risk in many countries from which it is absent. Information is needed on the radiation tolerance of important surface pests of quarantine importance such as F. occidentalis so that phytosanitary irradiation treatments for exported fresh commodities can be lowered to below the 400 Gy generic treatment currently approved for most insects in the United States and Australia. Lowering the dose will help minimize any product quality problems, reduce costs, and shorten treatment time. In large-scale confirmatory trials conducted in two independent laboratories in Hawaii and Australia, a dose of 250 Gy (measured doses 222–279 Gy) applied to adult F. occidentalis on green beans resulted in no reproduction in 5,050 treated individuals. At 250 Gy, the effective dose is significantly below the 400 Gy generic dose, demonstrating that irradiation at this lowered level is an effective method for the disinfestation of F. occidentalis from fresh horticultural produce.