Thermacell Patio Shield RepellerDESCRIPTION The Thermacell Patio Shield Mosquito Repeller is a compact and stylish device will look great on any patio or deck while it works to repel pesky mosquitoes. Ideal for use while entertaining. Thermacell Patio Shield is powered by a Thermacell fuel cartridge which creates heat to activate the repellent Allethrin, a synthetic version of a naturally occurring repellent found in chrysanthemum flowers. Heat disperses the repellent creating a 4.