In order to investigate the effects of three insecticides on three day-old L. fabarum females (Hymenoptera: Aphidiidae), the parasitoid of Aphis fabae, an experiment was carried out using IOBC/wprs method. Persistence toxicity of insecticides has been evaluated in the semifield condition. The trials were laid out in randomized complete block design (RCBD) with 3 replicates and an untreated check. The insecticides abamectin 1.8 EC, imidacloprid 350 SC, and pymetrozine 25 WP were used at recommended field rates. The insecticides were applied on broad bean foliage using a hand sprayer, until run-off. Contact toxicity of semi field-aged residues of insecticides on adult parasitoids was evaluated using the cage-method. The mortality of adult parasitoid, after 24 h contact with 1-day old residues of abamectin, imidacloprid and pymetrozine were 53, 90 and 57%, respectively. After 5 days the effect of residues decreased so that the adult mortality diminished to 28, 77 and 18% for mentioned above insecticides. 16-day old residues lead to 9, 22 and 14%; and 30-day old residues lead to 0, 3 and 1% mortality for these insecticides, respectively. Based on this study, abamectin and pymetrozine with persistence less than 5 d are classified as short lived (Class A) and imidacloprid with persistence between 5 to 15d, classified as slightly persistent (Class B) compounds.