The olive psyllid, Euphyllura straminea Loginova (Hemiptera: Aphalaridae), is one of the most destructive pests of olive orchards in Iran, causing substantial economic losses through nymphal feeding on plant sap, flower buds, and young shoots. Severe infestations can reduce tree vigor, induce flower bud abscission, impair flowering, and ultimately decrease fruit set and yield. The present study was conducted to evaluate the field efficacy of selected insecticides as potential alternatives to obsolete compounds for the management of olive psyllid nymphs in an olive orchard located in Azadshahr County, Golestan Province, northern Iran. Five insecticides, including Asphit, spirotetramat, abamectin, matrine, and spinosad, were applied at the recommended field rates in a randomized field experiment with three replicates. Nymphal populations were assessed one day before treatment and at 3, 7, and 14 days after application. Insecticidal efficacy was calculated using the Henderson–Tilton formula, and treatment effects were compared statistically. Significant differences were detected among the evaluated insecticides throughout the assessment period. Fourteen days after application, Asphit provided the highest level of control, achieving 92.36 ± 4.56% efficacy against olive psyllid nymphs, whereas abamectin exhibited the lowest efficacy, resulting in only 10.52 ± 3.77% control. Matrine also demonstrated substantial and persistent activity, reaching 83.10 ± 3.02% efficacy at the final evaluation. The superior and sustained performance of Asphit indicates its potential as an effective component of olive psyllid management programs targeting the nymphal stage. These findings provide valuable information for optimizing integrated pest management strategies in olive orchards and support the adoption of more sustainable pest-control practices while reducing reliance on high-risk insecticides and preserving agroecosystem stability.