Drift of spray droplets is a major problem in the application of insecticides and herbicides. Spray drift is the movement of the spray from the place of application to adjacent areas by wind or air currents. Many insecticides and herbicides are effective in minute quantities and even the small amount that drifts can be harmful to crops and livestock. Parathion, 2,4–D, and 2,4,5–T are among those chemicals whose drift is a problem where they are used.