Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Useless for cluster flies...

If you're buying this device for cluster flies, save your money. We've had it up for a week in different places around the house and the only thing inside it is a hapless ladybug that wandered into it. Hundreds of cluster flies cloud our windows and divebomb us as we walk from room to room. A bug zapper has been the better approach for euthanizing these annoying insects.