Insecticide Chemicals that kill insects, like bug sprays. Some are used on crops to kill any bugs that may eat them, but then you have to deal with washing the chemicals off before you eat the food.
and also....
An insecticide is a pesticide used against insects. They include ovicides and larvicide used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind the increase in agricultural productivity in the 20th century. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans; and others are concentrated in the food chain.
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A pesticide that is used to kill plants, or to inhibit their growth or development. Also known as weed killers.
Herbicide A chemical pesticide designed to control or destroy plants, weeds, or grasses.
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chemical substances or living organisms (called bioherbicides) used to kill or control vegetation such as brush, weeds, and competing or undesirable trees.
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A pesticide that is used to kill plants, or to inhibit their growth or development. Also known as weed killers.
Fungicide A pesticide that is used to kill fungi in plants, stored products or soil, or to inhibit their development.
(Chemicals that kill fungi for medical or veterinary applications are termed “antifungal agents”; they are classed as pharmaceuticals and so are not included in the Compendium.)
Acaricide A pesticide that is used to kill mites and ticks, or to disrupt their growth or development.