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What Is the Main Cause of Fleas? How Do They Get On My Pet?

Fleas trapped within a flea comb.

Determining what’s causing a flea infestation in your home can be difficult, especially if your home and pets are squeaky clean.

It’s even more of a mystery if you find fleas but don’t even have a pet.

What is the main cause of fleas? The vast majority of the time, flea infestations are caused by animals, as fleas need a host to survive. Pets are often to blame, but rodents can cause flea problems as well. Fleas may also be unintentionally brought into the home or yard on people’s legs or clothing.

Yes, fleas will use people as their hosts too. Let’s take a look at how animals (and you) can be responsible for fleas coming into your home.

The Main Cause: Animals

There’s no doubt that animals are usually the cause for fleas in the home. Fleas will make their home outside but will happily live in your home if they’re brought there.


Dogs and cats are the most common pets that will bring fleas inside.

Dogs and cats are usually the perfect hosts because they’re hairy enough to help the fleas hide and they’re low to the ground.

Fleas can jump up to 13 inches high, so even if your pet doesn’t lie down outside, they’re still easily accessible to fleas.

Fleas can easily jump from one animal to another.

If you take your dog to a park and they sniff another dog or your cat comes into contact with a neighborhood cat, the fleas can be transmitted.

Fleas are constantly looking for a suitable host to feed on, and they’ll quite literally jump at a new opportunity. 

Fleas don’t limit themselves to just dogs and cats, however. Mice, rabbits, ferrets, and other small, hairy animals can pick up fleas if they come into contact with them. 

If you adopt a new pet, be sure to inspect it before bringing it home and give it a good bath first thing. It doesn’t take too long for a few fleas to become an entire army. 


If domestic pets can bring home fleas, so can unwanted rodent visitors. You may not even be aware that you have mice or rats scurrying around your home.

Squirrels can also be a problem if there’s an opening in your attic.

When rodents have fleas, the eggs fall off them as they run in your home.

If the fleas survive until adulthood, they’ll make their way into parts of your home that have carpet or potential hosts.

If your pet doesn’t have fleas or you don’t have a pet, check your home thoroughly for droppings and places that could allow rodents to come inside.

If you spot any openings or damaged wood, repair and replace these areas as soon as possible.


You could be the missing link in the flea mystery if you don’t have pets or rodents.

Since fleas can jump, they can easily jump onto your ankles or socks and hitch a ride to your home, all the while sucking your blood.

If your ankles have become first-class transportation for a few fleas, they’ll hop off in your home or in your yard once they find suitable conditions.

If fleas are living in your yard, you’re a one-way ticket to the indoors if you’ve spent any amount of time in the yard.

(How long can fleas live? We explain that in this article.)

It’s smart to check your legs and feet for bugs of any kind before you go inside.

The Source

If you have fleas in your yard, walking through it once will be enough to bring them inside.

The key is to know what kind of conditions they like so you can do what you can to make your yard unfavorable to the fleas.

Fleas like the following conditions:

  • Shady and dark areas.
  • Humidity, but no more than 20%.
  • Protected areas like tall grass.
  • Dirt patches.

If you keep your grass short and your bushes trimmed, you have a smaller chance of having fleas.

Flowerbeds and overgrown areas are the most common places you’ll find them living.

They like to be protected from the wind and rain, so they’ll hide in the dirt under low bushes or in tall grass and flowers.

(Which do they prefer more – grass or dirt? Find the answer here.)

Fleas don’t like frequently watered areas because too much humidity will increase mortality rates and puddles of water will cause them to drown.

If you water your landscape frequently, you’ll decrease the chances of them living in your yard.

Attaching a programmable timer to your outdoor faucets can help make sure your yard is watered routinely on a set schedule (fleas will hate this).

Simply set the desired the desired start time, frequency, and duration, and the device will automatically control the sprinklers according to your wishes.

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Why Fleas Stay in Your Home

Fleas are likely to stay in your home because it’s warm, dry, and slightly humid. There are many dark places the fleas can hide, which increases their chances of survival. 

Fleas will stay in the following locations:

  • Carpets and rugs.
  • Under furniture.
  • On upholstered furniture.
  • On pet bedding.

They might occasionally live on beds if you or your pet bring them onto the bed, but this is less likely because they don’t like to be disturbed, which you’ll likely do at night.

You probably won’t see them in bathrooms since water frequently puddles on the floor and because they get too humid.

Pet bedding is the prime area where you’ll find them.

If your pet has fleas, eggs will fall off and land on the bedding, or the fleas will jump off your pet to lay their eggs.

Once hatched, the larvae will stay in the creases of the bedding. If your pet sleeps on blankets, there are many places for eggs to hide.

The carpet underneath furniture is also a common problem area because the carpet fibers allow the fleas to bury in and hide and they get overhead protection and shade from the furniture. 

If your carpet is infested with fleas, you’ll find the help you’re looking for in our article, “How to Get Rid of Fleas in Carpet.”

How to Prevent and Get Rid of Fleas

Once fleas are brought into your home, they can be difficult to get rid of.

Be diligent when using prevention and removal methods since a few are bound to stay behind and try to multiply.

You’ll find answers to common questions and practical solutions for dealing with these biting pests in our flea section, but for now know that you can win the battle with a bit of persistence.


Here are a few tips to follow to keep fleas from entering your home:


Check your legs and your pet for fleas before going indoors. Fleas can grab onto your pants, socks, shoes, or bare legs.

They like to hang around your pet’s neck and hindquarters the most, but they can be found anywhere.


Mow your yard, water your plants, remove debris, and trim your bushes.

What’s unappealing for a flea looks great to humans, so your hard work to keep your yard neat will give you double the reward.


You can make DIY sprays with citrus fruits, herbs, or vinegar to spray around your home (you can find the step-by-step directions here).

Fleas hate the smell of citrus and herbs like rosemary, so spreading the scent through your home will discourage them from staying.

Plants like lavender and chrysanthemums also keep them away.


There are several ways to get rid of fleas. You don’t even have to use pesticides. Here are a few methods:


Diatomaceous earth and salt are natural ways to kill fleas without harming people and pets.

Wait, salt – really? Believe it or not, yes, salt is effective when used correctly. Find out how here.

As fleas walk across the natural powder or grains of salt, their exoskeletons get cut, and moisture is pulled out of them. They’ll die from dehydration in just two days.

You can easily vacuum it all up (including the dead fleas) once you’re finished.

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Natural Poison

Boric acid is a natural poison that will kill fleas. It’s used in many carpet powders, but you can use it on its own.

It’s natural, so there aren’t added ingredients and chemicals.

Even though it’s natural, it’s still harmful if you come into contact with it or ingest it, so keep children and pets away from it.

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Pesticides are harmful to people and pets. They can cause respiratory and skin irritation if you come into contact with them. The effects can be lethal if they’re ingested.

However, they’re almost guaranteed to kill all fleas, whether they’re eggs, larvae, or adults.

Enforcer Flea Spray not only kills fleas on contact but also contains insect growth regulators to prevent any eggs from hatching and stop the life cycle in its tracks.

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If you’d prefer to use a powder form, head over to our article, “Best Flea Powder for Carpets” to view our top recommendations.


If you don’t mind paying for a quick fix, exterminators are the way to go.

They’re professionals, so they know how to use pesticides safely and effectively. Still, they use pesticides, which can be dangerous if you come in direct contact with them.

Final Thoughts

Animals can bring fleas into your home, and all the nooks and crannies that your rugs and carpet provide can be enough to convince the fleas to stay.

Removing fleas before you go inside and implementing prevention methods can help you keep them out of your home.

Don’t miss out on more useful information about dealing with fleas, both indoors and outside. Visit our other flea articles to learn more tips and elimination methods.