Physical Characteristics 
Fleas are parasites, which means that they are small organisms that live in or on (and at the expense of) a larger organism (the "host" animal). Some parasites cause no problems, others cause discomfort and annoyance, and still others can lead to life-threatening disease. Fleas are small, wingless insects that are parasites on dogs, cats, pigs, rodents, birds, and humans. Adult fleas suck the blood of their hosts, and they are known to survive for months while waiting for a victim to come by. 

There are several species of fleas, but the most widespread among both cats and dogs is the cat flea, Ctenocephalides felis. This flea's cousin, the dog flea, Ctenocephalides canis, also occurs, but is less common. 

Lifecycle 
Fleas have a four-stage lifecycle: adult, egg, larvae, and pupae. They flourish in the conditions that we find most comfortable--temperatures of 62-83 degrees F with 52% to 92% humidity--exactly where we keep our homes. 

A female flea can lay up to 25 eggs a day, and the cat and dog fleas are likely to lay those eggs on their host-your pet. After an incubation period, the eggs hatch.The newly hatched larvae burrow into dark, safe places such as your rugs and furniture and outdoors under leaves. The larvae eat dried blood and other organic substances for several weeks. Then they spin a cocoon and pupate. In their cocoons, the pupae are safe from insecticides and even very cold temperatures, sometimes for more than a year. The pupae hatch when they sense a meal is near. 

Over 95% of the flea population at any time is in the egg, larval, or pupal stage, which is why it's so important to use treatments that affect these stages. In the past, flea control has worked on the basis of killing off only the adults. Now veterinarians and pest exterminators recommend an integrated approach to disrupt the fleas' different life stages, hopefully resulting in fewer eggs hatching and growing into adults. 

Does My Pet Have Fleas? 
Fleas don't spend all of their time on your pet. In fact, they only spend about 10 minutes per day. They hop on to eat and lay eggs, and then hop off and hide in your carpet, your pet's bed, your yard, or some other flea-friendly place. 

Not sure whether your pet has fleas? Those tiny black specks on your pet or its bed and other favorite spots could be "flea dirt". Flea dirt is actually the adult flea's feces and is rich in blood-so rich that the larvae eat it for nourishment. Wet the specks with a drop of water and if they turn red, they're flea dirt. 

Another method is to use a flea comb, which you can get from your local pet store. (The metal combs work the best.) Run the comb over your pet, making sure to penetrate to the base of its coat. When you pull the comb off, if your pet has fleas you'll see either the flea dirt or the fleas themselves. Don't let the fleas get away-drown them in a bowl of soapy water before they can jump back on your pet. 

Problems Caused By Fleas 
The primary annoyances of fleas are those red, itchy bites that have you and your pets scratching in stereo. When a flea bites your dog or cat, it deposits a small amount of saliva in the skin. Your pet can develop an allergy to this saliva and react with severe itching. This condition is called flea allergy dermatitis. It mostly affects dogs, but cats are susceptible, too. Common symptoms are biting or scratching excessively around the tail, groin, or backside or the appearance of small scabs or bumps on the animal's neck or back. 

Fleas can also carry tapeworms, one of the most common internal parasites and one you will actually be able to see. If your pet in infested with fleas, it's also possible that it might have tapeworms. You can read more about tapeworms in Taking on the Tapeworm. 

Treatment and Prevention 
One of the most common errors that pet owners make is to treat only one of the flea's life stages. If you are using a flea shampoo or dip, you're only killing the adults. To achieve the best results, treat comprehensively. And be prepared to repeat the treatment. Flea control is an ongoing process. 

When planning your strategy, you'll want to keep several things in mind. Do you want to use chemical treatments? Or do you prefer the all-natural approach? You can also combine strategies, using, for example, the all-natural treatments first and then supplementing your efforts if necessary with chemical treatments. 

Many products that are on the market contain a flea-growth-hormone inhibitor. These products work by preventing the immature fleas from becoming adults. Then there are the "adulticides" (such as shampoos and dips) that kill the adult fleas. Using an integrated approach to controlling both immature and mature fleas will most likely yield the best results. 

Remember that using chemicals, while very effective, can be very dangerous to you, your pet, and the environment if you don't follow the directions to the letter. Also, combining pesticides and other chemicals can create health hazards. Use chemical treatments responsibly-and always keep them out of your children's reach. 

Many pest control manufacturers offer a line of integrated products that are designed to work together, greatly simplifying your decisions. Above all, plan an approach that works for your geographical area, your lifestyle, and your safety. If you have tried several strategies over the years, and still can't seem to control your flea problems, ask a local veterinarian for recommendations that are specific to your region. 

You will want to plan on treating your pet, yard, home, and car (if your pet rides with you) all in the same day. You might even want to drop off your pet at the groomer's and treat your living areas while Fido gets dipped. If you have cats and dogs in your home, treat them at the same time. 

First Things First 
First, vacuum and mop to get rid of as many immature (eggs, larvae, and pupae) fleas as possible. Try vacuuming up some flea powder to kill any fleas that get sucked up into the bag. After you vacuum, dispose of the bag (in the outside trash container) immediately, so the fleas that are trapped can't use it as a safe place to hatch and reinfest your home. 

There are many options for treating your home, including carpet powders, sprays, and foggers. Give extra attention to your pet's bedding and favorite spots around the house (carpet and furniture). Follow the directions on the label exactly, making sure that your family, your pets, and food (pet and human) are not exposed to unsafe chemicals. 

Next stop, the great outdoors. By treating your yard, you can eliminate many immature fleas and stave off a frustrating reinfestation. When choosing the outdoor product, make sure it's compatible with the other products you are using on your pets and inside the house. Mow the lawn and rake up any leaves, brush, or clippings. Then spray your yard, concentrating on dark, leafy areas and your pet's favorite spots. 

Flea shampoos and dips come in many varieties, including all natural. All kill the adult fleas and provide some residual protection. Pay close attention to the instructions on the label, including any limitations on using the product on young animals or on animals that it was not formulated for. (For example, a dip formulated for adult dogs can be highly toxic to cats or young animals.) 

After the bath, you may want to use a sponge-on treatment. These treatments generally are left on your pet to dry. Between baths, a flea spray can help keep fleas off your dog. 

Since the recent release of the once-a-month pill for dogs, these breakthrough treatments seem to be coming out fast and furious. A similar once-a-month oral suspension for cats was recently introduced. Additionally, new spot treatments that last up to a month are due to be released soon. Consult your veterinarian for a recommendation (and prescription for your pet if you decide to try it). 

Note from Jack Vanderwyk, author and Labrador breeder: 
"I have lived with dogs since I was a child. From the moment I started to live on my own, I was about 21 I guess, I always had dogs in the house, at least 5 of them, usually more. Hairy ones too, a Polish wolf and several Bouviers des Flandres. Never had a problem with fleas and I didn't treat the dogs with any anti-flea stuff. Sure, they did have some fleas once in a while, but only a few, and for a short time. 
In 1991 I got my first Labrador. Ten years later I had 21 Labradors, recently I reduced the stock to 12. Never had any flea problems with them either. I never wash the dogs, I just let them swim in clean water. Fleas seem to think my dogs aren't attractive creatures. I guess my dogs have some natural antibody against fleas, which they could develop because they were never exposed to anti-flea chemicals, and neither were their parents."