These are substances that attract insects through sensory stimulation. In nature,
it is seen in their response to the odor of food, to the opposite sex, to prey, and to sites
for egg deposits. Attractants are used in control programs to induce insects to eat
poison baits or to lure them into traps either for actual control or for determining
There are chemicals that are not primarily toxic, but add to the effectiveness of
pesticides. The major types of materials now used are emulsifiers, wetting agents,
stickers, solvents, dust carriers, and synergists.
Section II. PESTICIDE FORMULATIONS
2-6. DUSTS (D)
A dust is a dry mixture that usually consists of an active pesticide mixed with talc,
clay, or some other inert powder used as a diluent, or carrier. Dusts are usually low in
cost, easy to apply, nonstaining, nontoxic to plant life, and generally not readily
absorbed through the skin. They may be dangerous, however, if inhaled into respiratory
passages. Since they are dry, they are the preferred formulation for use around
electrical connections. Due to the small particle size, dust can be used to penetrate
small cracks and crevices. Two disadvantages of dusts, in addition to the respiratory
hazard, are that they do not adhere well to vertical surfaces and they are easily
removed by wind and rain.
2-7. GRANULES (G)
Granules are large particles or pellets varying from 400 to 800 microns in size.
The granules are usually impregnated with 5 to 25 percent of the toxicant. The granular
form of insecticide is particularly desirable in mosquito breeding areas covered by heavy
vegetation that is not easily penetrated by sprays.
2-8. WATER WETTABLE POWDERS (W OR WP)
Suspensions are prepared by diluting water wettable powders with water and
thoroughly mixing. A water wettable powder is a toxic ingredient blended with an inert
dust to which a wetting agent -- usually a soap or detergent -- is added to facilitate
mixing the powder with the water. This forms a suspension in which the fine particles
are suspended -- not dissolved -- in the water. Suspensions require constant agitation
during application to prevent solid particles from settling to the bottom of the sprayer.
They are also more prone to clog the nozzles of sprayers due to their large particle size.