Insecticide is a type of chemical used to kill insects, like those that have infested a house or a farmer's crops.
Words that end in -cide usually have to do with killing, such as genocide, suicide, and patricide. Another is insecticide, which is a word for a substance that kills insects and bugs. Insecticide is a type of chemical, and it often consists of a powder or gas. If your house is full of bedbugs or cockroaches, you need insecticide. Farmers sometimes use insecticides to keep insects from destroying crops. If you're a bug, insecticide is bad news.