The effectiveness of a plastic collar designed to protect planted seedlings against damage caused byHylobius abietis(L.) (Col., Curculionidae) was evaluated at 63 planting sites in southern Sweden during 1979 and 1980. Nearly 10 000 collar‐protected pine and spruce plants and 10 000 controls were carefully examined forHylobius‐damage and other injuries. In addition, the impact of some microsite factors on weevil damage and collar performance was evaluated, and the height growth was measured. The protective effect of the collar for two seasons after planting was comparable to that of insecticides and was best at sites with sparse vegetation and high weevil pressure. Proper application of the collar was crucial for good control. Collars were not observed to affect plant growth. Soil scarification reduced mortality in both collared plants and controls.