The Culex mosquitoes that usually spread West Nile tend to bite at sunup and sundown, which is why risk is heightened at those times of day.

• 库蚊通常于黎明和黄昏时分出现，并通过叮咬来传播西尼罗热病毒，这就是为什么这段时间是一天中最为危险的时候。