A pesticide is any chemical used to control pests. Often confused with insecticides, pesticides are a larger term to describe insecticides, herbicides, fungicides, and all other chemicals for various pest control applications.
Pesticides can work in various ways. Some work by contact, meaning that the chemical only needs to touch the target pest to begin working. Some need to be ingested, which is common for insecticides. Others work systemically, meaning that they can be absorbed, injected, or fed to plants or animals. When the target pest feeds on the plant or animal, they ingest the pesticide.
Sometimes pesticides are targeted for specific pests, like narrow spectrum insecticides that affect certain insects or selective herbicides that only affect specific plants. Some pesticides aren’t targeted. Non-selective herbicides will affect all plants, and broad-spectrum insecticides will affect multiple kinds of insects (but not all).
There is always concern about the safety of pesticides. Some are dangerous to humans and require high caution when applying. Others are dangerous to mammals and aquatic animals and runoff that gets into lakes, rivers, and streams can do serious damage to these animals. However, there are now extensive databases that list dangerous pesticides so you will be able to choose safe pesticides .