 The mosquito most common for transmitting West Nile is the Culex tarsalis. This mosquito is most active from sundown and throughout the night into the early morning hours. The health department recommends use insect repellent that contains DEET. Limit outdoor activities between dusk and dawn when mosquitoes are most active. Wear long pants and long-sleeve shirts when possible. Eliminate standing water from buckets, flower pots, old tires, wading pools, and bird baths.