Mists are dispersed particles in which the particles are intermediate in size between those of aerosols and fine sprays. Droplets in the 50 to 100 micron size range are considered to be mists. They are less effective than aerosols for outside space treatment, but they are adaptable for larviciding in areas accessible to vehicles and for large scale residual spraying of vegetation. Because of their larger size, mists can be used under a wider range of weather conditions than can aerosols, and their residual effect is greater. Mist formulations may be either oil solutions or water emulsions.
Sprays are the most commonly used formulation.
Fine spray droplets are considered to be from 100 to 400 microns in diameter. Droplets within this range remain airborne short periods of time and settle rapidly. Sprays of this type are frequently used as mosquito larvicides and for residuals. These sprays consist of droplets over 400 microns in diameter and are applied evenly to wet a surface. Coarse sprays are frequently employed when using herbicides and when applying heavy residuals of insecticide to fly breeding areas.