This article is from the Fleas, Ticks, and Your Pet FAQ, by tittle@zmall.com (Cindy Tittle Moore) with numerous contributions by others.
To check if your pet has fleas, part its hair and look for:
* Small bits of brown "dust," attached to the fur itself. The fleas
excrete digested blood. See if the dust dissolves into a red
liquid upon contact with a wet paper towel.
* Skin Irritation: flea bites or scratching and biting may leave
red, irritated skin, and even bald patches in bad cases.
* Small, fast moving brown shapes are fleas.
* Or, use a flea comb and see what you get.
You may also see "flea dust," fleas, or even larvae on your pet's
bedding.
Dried blood in its ears may indicate ear mites and you should consult
your vet to find out what the problem is.
 
Continue to: