They look like dusts, but they are made to mix with water. These formulations need continuous agitation to maintain a suspension and are thus difficult for home gardeners to use. The spray tank must be frequently shaken to maintain the suspension. A bait formulation is made by adding the active ingredient to an edible or attractive substance. Baits are often used to control slugs, snails, ground-dwelling insects, and rodents.
Gardeners often attempt to compare a spray with a dust.
When added to a pesticide, a surfactant reduces the surface tension between two unlike materials, such as a spray film and a solid surface. For example, by adding a surfactant to a sprayer, oil and water will mix and can be sprayed on plant surfaces. With increasing emphasis on safe application of pesticides, such factors as droplet size, spray pattern, and pesticide drift have focused more attention on surfactants to give ideal coverage for pesticides. This section focuses on surfactants that act as spreading, sticking, and wetting agents. Whether a spray rolls off or sticks to a plant surface depends on the physical and chemical properties of the spray mixture and the physical properties of the surface itself.