Common Types of Adjuvants in Pesticide Formulations

Solvents Organic molecules are not always soluble in water.   Solvents such as xylene, acetone, or oils may be necessary to produce a homogeneous formulation.
Emulsifiers Like the dish detergent that lifts grease off a dirty plate, these soap-like compounds break up oily solvents into microscopic "bubbles" and suspend them as colloids in a water solution.
Spreaders Often called wetting agents, these compounds reduce the surface tension of water, allowing droplets to cover a larger surface area and to penetrate further into small cracks.
Stickers Also known as adhesives, these compounds are added to an insecticide to improve its adhesion to target surfaces.   Spray stickers help prevent wash-off during a rain.
Buffers Some insecticides are sensitive to pH (acidity or alkylinity) of water.   Buffers can be used in a formulation to help stabilize pH of the final spray solution within an acceptable range.
Thickeners In some cases it may be desirable to increase the viscosity of an insecticide formulation.   Used in a spray solution, these adjuvants help reduce drift by increasing droplet size.
Baits Insecticides that must be ingested are often formulated with some type of bait or feeding stimulant.   Buffalo gourd root powder, for example, is added to some formulations as a feeding stimulant.
Synergists By themselves, these chemical agents are not toxicants, but when mixed with an insecticide they significantly enhance its lethal effect.   Synergists are typically used with pyrethroid insecticides to block the activity of detoxification enzymes.
Abrasives Certain substances, such as silica or pumice, can improve the efficacy of a formulation by abrading the protective wax layer from an insect's exoskeleton and improving the dermal penetration of toxicants.