Ward off pest aphids on roses with a natural pheromone that alarms aphids and causes them to stop feeding and eventually move on or die of starvation. Non-toxic dispensers do not affect beneficial insects and control most prevalent aphids types, especially Green Peach Aphid, the most common species that attacks roses. One dispenser hung on each infested rose plant wards off aphids in 5 to 7 days. Dispenser work for 3 to 4 weeks. Apply dispensers early in the season to prevent aphid colonies from becoming established. Package contains 4 individually wrapped dispensers, enough for one full season.