Plum curculio females,Conotrachelus nenuphar(Herbst) (Coleoptera: Curculionidae), were found to oviposit, before fruit set, on mature ‘Granny Smith’ apples attached to major branch junctions in the upper half of standard ‘McIntosh” apple trees. Observations for three growing seasons (1978, 1979, and 1980) within an insecticide-free orchard in southwestern Quebec are presented. Rank correlations between oviposition on these scout-apples and both “June” drop and harvest damage were found. Incidence of scarring was highest (17 to 25% of scout-apples had oviposition scars) in orchard sectors adjacent to a woodlot and lowest (7%) in the central sector of the 1.7-ha experimental orchard. This monitoring technique may be used in apple orchards to indicate when and where to concentrate control efforts.