A pest is a plant or animal which affects human and crops, there are various types, and all are categorized into various groups. Below are what pests do.
They can damage clothing that is by making holes in clothes
Grasshoppers and caterpillars eat and attack cereals and vegetables
Mosquitoes are known to carry microorganisms that cause diseases
Bed bugs, on the other hand
are hand to control, and they do bite people a lot
Termites damage buildings
Mites and rats damage stored food
All pests damage something, and controlling them is not easy, but when you know which pest is damaging your crops, telling what to use becomes easy. As for the case of pests such as bed bugs, you need to be extra clean with your beddings and use the right spray that kills them.
You can get help from an agro vet if you find it hard to handle; they will help recommend the best medicine for you since they are professionals.