The Flea Days of Summer
August 3, 2008
An archive of Pet Columns from the University of Illinois College of Veterinary Medicine is available online at Requests for reprints of this article may be directed to Mandy Barth,

Summer is now in full swing and so is the war against the tiny, wingless, blood-eating fleas that make our pets miserable during these hot, humid days.

The flea, while extremely annoying to both pets and humans, is actually quite a fascinating insect. According to Dr. Allan Paul, a veterinary parasitologist at the University of Illinois College of Veterinary Medicine in Urbana, the life cycle of the flea is divided into several stages: egg, larva, pupa, and adult. The flea's body is flattened slightly to allow it to move between the coarse fur of a cat or dog with ease. The long, specially adapted legs of a flea allow it to jump up to 200 times its own body length, making it the best jumper in the animal kingdom.

Adult fleas will spend the majority of their lives on a host animal if they are able to find one. Once on the host, an adult female flea can lay up to 50 eggs per day, or about 2,000 eggs in a lifetime. These eggs will then fall off the animal and hatch into larvae within a few days.

Dr. Paul explains that these larvae will then develop in the environment, thriving in warm, moist, dark places like under furniture, decks, and yard waste. Within 7 to 10 days the flea larvae will form a cocoon, entering the pupa state. With the proper conditions, the pupa will develop into adults within 1 to 2 weeks.

The pupa is a resilient life stage for the flea and, if conditions including heat, vibration, and carbon dioxide are not right, the pupa may not emerge from its cocoon for months. There is no life stage of the flea can survive freezing, which is why flea populations and infestation problems decline significantly after the first frost of the year. However, the pupa stage does have the ability to survive the winter in indoor environments and in areas where freezing and frost does not occur. This means that pets are susceptible to fleas year round.

"Unfortunately, the hot and humid summer days in the Midwest lend the ideal conditions for flea development and during the summer the flea life cycle will take around 28 days to complete," explains Dr. Paul "Thankfully, preventing and controlling fleas is much easier today than it was a decade ago as safer, more effective, and easier to use products have become readily available to the public"

According to Dr. Paul these stand alone topical and oral flea preventatives are usually enough to stop any flea infestation in its tracks. However, in cases of heavier infestations your veterinarian may recommend increasing the frequency at which the preventative is applied or spot treating the areas in your home or yard where fleas thrive. Dr. Paul also advises that you should never make any changes to your pet's flea prevention regime without consulting your veterinarian.

While the majority of the products on the market will work to some degree, not all flea preventions are created equal, making it best to purchase your flea preventative from your veterinarian. The products available through a veterinarian may combine flea prevention with heartworm, tick, intestinal parasite, or other external parasite preventative medications. Oftentimes you can simply apply a liquid product or give your pet a chewable tablet once a month to make sure your pet is protected against fleas and the plethora of other parasites that may threaten your pet. As always, consult with your veterinarian to decide which products and control programs are best suited for your pets.

Sometimes, despite your pet being on the best flea preventative on the market, fleas may still appear. Dr. Paul explains that if you find yourself in this situation don't panic. No product on the market is able to kill fleas instantly. Give your pet's medication some time to work; the fleas that you might see have likely not bitten your pet yet and will die before laying any eggs.

"The best way to look for fleas is to check your pet for flea dirt, a pepper flake-like substance that is actually flea feces," says Dr. Paul. "The most likely place to find flea dirt is at the base of the tail or any other area where the animal usually cannot reach to groom."

If you are administering a preventative medication after an infestation has already occurred, it is important to remember that preventative medications work best if given before fleas have a chance to jump onto your pet. Once the medication has time to circulate through your pet's system you should see a huge difference in the flea population.

Dr. Paul recommends thoroughly washing your pet's bedding and vacuuming your house, including under and on the furniture and any other area in which your pet spends a lot of time. This will remove a large portion of the eggs, larva, and pupa that reside in these areas. Bathing your pet will help to remove the adult fleas and give your pet some relief until the flea medication has a chance to take effect.

After the flea problem has been cleared from your pet and home Dr. Paul recommends that owners should be on the lookout for any sign of an intestinal parasite called the tapeworm. Some signs of infection include the appearance of rice-like worm segments in the feces or on the animal, unexplained weight loss, and lethargy.

Your pet can become infected with this parasite by accidentally ingesting fleas, which will happen when your pet grooms itself or bites at the fleas. It is important to remember that the tapeworm is a zoonotic parasite, which means that the both the two-legged and four-legged members of your family are susceptible to infection if a flea is accidentally ingested.

If you have any questions about fleas or how to protect your pet against this pesky parasite, contact your local veterinarian.

An archive of Pet Columns from the University of Illinois College of Veterinary Medicine is available online at Requests for reprints of this article may be directed to Mandy Barth,

Veterinary Extension/Office of Public Engagement
University of Illinois College of Veterinary Medicine