If you have an extra-large mosquito problem, the Dynatrap XL Mosquito Trap delivers several layers of powerful protection. First, a UV fluorescent bulb generates a warm light, attracting mosquitoes.Then, a powerful yet whisper-quiet vacuum fan sucks them into the retaining cage where they dehydrate and die. Empty the retaining cage every 1-2 weeks and replace the UV Bulb every 4 months or 3,000 hours