The Zevo Flying Insect Trap uses blue and UV light to attract flies like gnats, house flies, and fruit flies. They get stuck on a powerful adhesive pad inside the cartridge and can not escape. For best results, try moving the trap to a different spot where you see more flies. Also, make sure the blue light is on, showing the cartridge is properly inserted. Check the cartridge every 15 days and replace it when full. Our products undergo rigorous quality checks, and your feedback is important to our Quality Assurance Team. We would love to hear more about your experience and assist you further, so please call us at (866) 215 1297.