What is a contact insecticide?

Contact insecticides are used to get rid of sucking insects such as aphids and spider mites. Malathion insecticide is one of the best, but there are many others, such as many organic pesticides, chlordane, lindane, and nicotine. While some have a residual effect and will also kill insects that chew foliage, all are more effective when they actually strike the insects. So it’s important when using them to spray or dust every part of a plant.