Culex mosquitoes are a genus of mosquitoes commonly found in many parts of the world. They are known for their role as vectors for various diseases, including West Nile virus and Japanese encephalitis. Culex mosquitoes typically breed in stagnant water, such as ponds, marshes, and containers, where they lay their eggs. These mosquitoes are most active during dusk and dawn, feeding on the blood of birds, mammals, and sometimes humans. Their presence can be a nuisance, and controlling their populations often involves eliminating standing water and using insect repellents to reduce bites.