Doktor Doom Spider Mite Knockout features a high-concentration of the naturally occurring insecticide pyrethrin, a very effective substance used to control aphids, spider mites, whiteflies, leafhoppers, Japanese beetles and more. Its one-fifth percent pyrethrin concentration is 10 to 20 times that of comparable pyrethrin-based insect control products. This powerful spray can be used indoors and out and is safe to apply on food crops up to one day before harvest.