Herbicides - used to kill unwanted vegetation, either selectively or generally. Molluscicides - used to kill snails and slugs. Repellent - a pesticide that keeps or drives insects or other pests away from the plant, animal or treated surface. Rodenticides - used to kill rats, mice, and other rodent pests. Insecticides - materials used to control insects.
Some insecticides kill both by touch and by ingestion.
Insecticides vary in the numbers of different kinds of insects they kill. Some insecticides kill only a few kinds of insects. These insecticides are beneficial when you wish to kill only one insect pest and not kill beneficial insects in the area. Other insecticides are a general purpose or wide range killers. No broad spectrum kills all insects.