Find instructions for a particular Sevin liquid insecticide product on the label of the product you are using or by locating the instructions of a particular product on the manufacturer's website, GardenTech.com. GardenTech.com offers a downloadable PDF of each of its products' specific instructions.
Sevin liquid insecticide comes in both a ready-to-use spray and a concentrate. The latter requires more preparatory work.
Sevin liquid insecticide uses a broad-spectrum chemical called Carbaryl to adversely affect the nervous systems of a wide variety of garden insects, such as beetles, cutworms and grasshoppers. It is generally safe for most vegetation.
SFGate.com advises donning protective equipment during the application process to prevent the liquid from getting on your skin or being ingested. The website also advices keeping people and animals out of the area while spraying.
If using a liquid concentrate, shake the product vigorously before mixing the specified amount of concentrate with the recommended amount of water. Shake again to mix the solution. Use a chemical-resistant sprayer to apply the mixture to the stems, branches and leaves of affected vegetation.
SFGate.com recommends working backward to prevent the chemical from getting onto your clothing. If possible, apply the insecticide on a dry day with little to no wind. The solution can be reapplied weekly until the offending insects disappear.