Fleas, ticks, and mites are ectoparasites, parasites that live
on or burrow into their hosts' skin. Parasites live at least
part of their life cycles at the expense of host organisms. They
can cause blood loss, skin irritation, allergies, and disease.
Some parasites live continuously on a single host, and others
live intermittently on their host. Many parasites spend as
little as 10% of their life actually feeding (i.e., living) on a
host. Some live on different host species at different stages of
their life cycle (e.g., ticks that carry Lyme disease live on
white-footed mice as larvae, and on deer or other mammals as
adults). Some can live on various host species, and others are
restricted to a specific host species, often to a single area of
the host's body. For example, demodectic mange is caused by a
hair follicle mite and is usually found only on the head or
legs. Hosts provide a number of essential resources for
parasites, such as: * Food (sweat, blood, tears) * A warm,
moist, protected environment * Tr