Parasites are organisms that feed on or derive nourishment from other living organisms known as hosts, often to their detriment. Several species of arthropod (insects such as mosquitoes and arachnids such as ticks) live on or within the skin of humans and animals. These pests are known as ectoparasites and many survive on the blood of their host.

They may be transmitted from animals to humans, from humans to humans, or from humans to animals. In addition to the irritation and public health nuisance caused by their bites, some ectoparasites have the potential to transmit disease-causing organisms. Some common ectoparasites that you would encounter in your daily life include: