A gnat, for one, is a small flying insect that belongs to the family of Culicidae. It is often seen in warm climates and is known for its annoying buzzing sound. Gnats are also known as 'nuisance pests' because they can be a nuisance to humans and animals alike. They can also spread diseases such as malaria and West Nile virus. Gnats are usually controlled by using insecticides or other methods of PEST control.