I've monitored these devices for over a week. So far it's working fine outside on repelling mosquitoes, flies, and small bees but not the queen bee. Every year my backyard would be swamped with mosquitoes, flies hovering my patio door, and bees making hive near the door. But not this year, after plugging in these repellers, I haven't seen any mosquitoes near my house even on hot humid days. But I have to say, I do use more than one outside because we have a creek running behind our house and tha...