Climatic and weather conditions directly affect the necessity for mite treatment in citrus, the number of applications needed per year, the type of application required and the effectiveness of acaricides used. The property of acaricides to be translocated is less advantageous, even for foliage applications, when made during the cooler periods of the year. Seasonal changes of the host and the direct or indirect influence of weather on the mite and the host are essential factors determining mite control and treatment scheduling under California conditions.