Fleas are the most common external parasite found on common household pets, such as dogs and cats. While they can be found on humans, they prefer non-human hosts. Fleas usually require warm and humid conditions in order to develop, so while they prefer the warmer months, once they are inside they are active year round. Fleas average in size from 1/12 inches to 1/16 inches long. The have no wings, but they have the ability to jump seven to eight inches vertically, and up to sixteen inches horizontally.
Infestations of fleas can grow very rapidly as female fleas can lay up to 400 eggs. The most common indication that you have fleas is seeing your pets scratching and biting themselves. People may also be bitten which can leave itchy red marks. You may also see flea “dirt”, which is really flea feces, and it looks just like small black marks that will most likely be around where the pets or people spend a lot of time.