Abstract: When a pesticide is applied in a vineyard, a fraction of the sprays can drift from thetarget and affect the abundance of beneficial arthropods. A field experiment was conducted inNorth-Eastern Italy in order to evaluate the spatial pattern of pesticide drift in a vineyardhedgerowsystem, and its effect on the predatory mite Kampimodromus aberrans. Threescenarios of decreasing potential drift were compared with or without hedgerows: a worst casescenario where the nozzles facing the hedgerows or the adjacent field were not closed, a goodagricultural practice scenario where the nozzles were closed and a no-treatment scenario. In theworst case, without hedgerows, 12% of the applied rate drifted for 6-7m and affectedK. aberrans abundance in the adjacent crop. The presence of a hedgerow reduced the drift byabout 80%. The hedgerow was also effective when good agronomic practice was followed, andthe effect of drift on K. aberrans was not significant. Because of lateral drift, fall-out drift wasdetected at very low concentration even in an untreated vineyard, posing a risk to surface waterand bystanders. This suggests that environmental regulatory schemes taking hedgerows intoaccount should be supported and implemented on a multi-farm or regional scale.