Defend against mosquitoes and bugs with our Patio Shield Repeller in vibrant red. Create a bug-free oasis for your outdoor activities. Get yours today! Keep mosquitoes out of your backyard gathering with the Thermacell Mosquito Repellent Patio Sheild in Red. This high-tech mosquito trap works by heating allethrin through a thermocell tank cartridge. Allethrin is a synthetic version of the natural repellent found in chrysanthemum flowers. Thermacell Mosquito Repellent Patio Shield creates a 15-foot protection zone and shields millions yearly from annoying mosquito bites without DEET, lotions, or unpleasant odours. Wait 10 to 15 minutes for the protection zone to activate for best results.