Fleas are medically important because of their worldwide distribution, abundance, and irritating bites that can cause health problems.
Fleas infest birds and mammals, including people, and are especially abundant on rodents.
The most common flea on people in Delaware is the cat flea. Other fleas such as dog fleas, human fleas, Oriental rat fleas, and several rodent fleas turn up only occasionally as human pests. Nature designed fleas to move freely among the hairs and feathers of their hosts. They are easily disturbed while feeding and may run or jump away using hind legs especially adapted to jumping. They are sparsely covered with hairs.