Sharon Billings, CVT
Senior Veterinary Information Specialist

Looking through the Pet Poison Helpline® blog archives, I see that we discuss external parasites a LOT, especially during the spring and summer.  Dealing with the bugs that bug us can definitely be a frustrating, time consuming, labor intensive business!  One bug that is especially vexing is the flea.  It can seem that no matter what we do or how hard we try, there are always fleas – everywhere!  This post will explain why that’s the case and what can be done to keep your home and your pets flea-free!

The Flea You See (the tip of the iceberg)!

Let’s say earlier this spring you and your dog had a lovely play date at the neighborhood dog park.  The next day, as you were petting her, you saw a very small critter moving quickly between her ears.  YIKES – A FLEA!   You sprang into action with a flea comb and a squeeze-on pesticide treatment.  You breathed a sigh of relief, confident you’d nipped this problem in the bud.

All was well until about a month later.  Once again, while giving your dog’s coat a good brushing, you spotted a little critter zooming across her skin . . . and wait —  another . . . and another?!  She was crawling with fleas!  You hadn’t even been back to the dog park – what’s going on here?

Well, it all has to do with the way fleas reproduce, a.k.a. the flea lifecycle.  Each creature has its own lifecycle, its means of reproducing to ensure continuation of its kind.  In the case of fleas, this is a job for which they are well equipped!  So the flea you see can truly be “just the tip of the iceberg”.  And the sad news is, once you see that first flea, you (your pets and your indoor / outdoor environment) are at risk of having an infestation.  An infestation simply means a flea has been in your home long enough to mate and lay eggs.

The Flea Lifecycle:

Everyone is familiar with the way caterpillars spin a cocoon and emerge as beautiful butterflies.  Well, fleas have a similar lifecycle (although there is no beautiful creature involved).  It goes like this:

Adults make up about 5% of an infestation.  Adults feed (on blood from a host, e.g., your pet) and mate within 12-24 hours of their life; females then lay eggs within 24 to 36 hours.  Females can lay 40 to 50 eggs a day.  Adult fleas actually spend little time on your pet – they just want the blood meal that they need and then they’re on their way.

Eggs make up about 50% of an infestation. Eggs (a bit smaller than a grain of sand) may be laid on your pet and then scattered in the environment as your pet moves about the house.  Eggs hatch as larvae in 1 to 10 days depending on heat and humidity.

Larvae make up about 35% of an infestation.  They are about ¼” long, white-to-translucent in color, and legless.  They live off of organic debris in the environment and within 1 to 2 weeks spin themselves into a cocoon and develop into pupae.

Pupae make up about 10% of an infestation.  This stage is extremely hardy and resistant to all insecticides (cannot be killed).  Cocoons have a sticky outer coating that allows them to hide deep in carpeting and crevices and they cannot be removed easily by light vacuuming or sweeping. The cocoon serves to protect the developing adults from chemicals.  This stage lasts anywhere from 5 days to 6 months – or even longer — and emergence of the adults is triggered when the pupae sense the potential presence of a host:  changes in carbon dioxide levels (mammals breathing), vibrations / body heat / and shadows (mammals moving about).  Creepy and disturbing, isn’t it?

Why Worry?

Of course, fleas are a nuisance – their movement and bites can cause itchiness; some pets (and people) are allergic to flea bites and have more significant reactions.  Additionally, fleas transmit parasites such as tapeworm when they bite.  If an animal’s flea burden is heavy enough, the animal can lose enough blood to become anemic.  All good reasons to do everything possible to keep them away from your home and pets!

What To do?

So . . . getting back to that one lone flea you found on your dog last spring.  Let’s say that before you found her, she managed to lay eggs that were then scattered around your home.  Those eggs eventually hatched into perhaps 30 fleas which in turn reproduced and this resulted in potentially hundreds of fleas!  Just imagine dozens . . . waves . . . armies of blood-thirsty fleas hatching out at varying intervals . . . all the time!

This explains why it can take up to several months to get that flea population knocked down and under control.  This can be time-consuming, labor intensive, expensive, and frustrating.  There is no magic bullet, but there are some steps you can take to keep you, your pets, and your home flea-free.  And as you might expect, an ounce of prevention is worth a pound of cure!

• The best offense is a good defense! Use preventives on all pets regularly.  Especially in warmer climates, you may need to use preventives year-round.  Those in colder climates may get a bit of a break as fleas are not as successful surviving in very cold weather.  If you do stop flea control over the winter months, start back up nice and early in the spring – before you see a flea.
• Think “WE” have fleas: Don’t think in terms of one pet having fleas because that’s where you saw them.  Once you see a flea on a pet, consider it a household-wide issue.  To keep fleas from moving on from a treated pet to a non-treated pet, use a species-appropriate product on all pets and treat all pets at the same time.
• Treat the indoor environment: To help reduce the flea population more quickly, remove eggs before they can hatch, breed, and increase their numbers.  Vacuum every day and discard the bag / empty the canister so the eggs don’t hatch in your vacuum cleaner!  Wash bedding or put it in the clothes dryer on high heat for 10 minutes to kill eggs.  Consider insecticide foggers.
• Treat the outdoor environment: Of course, we can’t remove every single flea from the great outdoors but consider using outdoor treatments to reduce the population in the area surrounding your home.

As always, we recommend you consult with your pet’s veterinarian for specific advice or for flea product recommendations that would be best for your pets.

Just one final note – double check to make sure any preventive product is labeled for your pet’s species.  In a multi-species home, this includes double checking with each use just to make sure you didn’t grab the wrong product by mistake!  Some products, safe for dogs, are very unsafe for cats . . . some products, safe for dogs or cats, are very unsafe for rabbits.  Just a couple examples, so always be sure to read and follow labels carefully!