10 Facts About Fleas

Sandra C. Mitchell, DVM, DABVP
By Sandra C. Mitchell, DVM, DABVP on Jul. 6, 2022
woman brushing husky outside in field

Fleas are insects that negatively impact the lives of many pets and their families, but they can be prevented by understanding the facts about fleas and flea infestations. Doing so will save you money, effort, and the hassle of dealing with a flea infestation.

Fleas Have a Flexible Life Cycle

Fleas are blood-feeding parasites that are more common and reproduce faster in warmer climates than in colder ones. They can, however, survive in a heated home during winter. Adult fleas are tinier than a grain of rice (1/8 inch or up to 4 millimeters). They are flat with no wings but are very strong jumpers.

It is harder to rid your pet and home of fleas in the winter because of a flea’s long life cycle, compared to a shorter one in the summer. Adult fleas can live up to one year in favorable conditions. Even if they are totally deprived of food, they can still survive for several weeks.

Female Fleas Can Lay Up to 40 Eggs a Day

An adult female flea can lay up to 40 eggs a day. This translates to 1,085 eggs, on average, for one adult female over its life span. That’s a lot of baby fleas from one female! The eggs are not sticky, so they fall into carpets, cracks in wood floor planks, pet bedding, and grass.

The eggs lie dormant for 2 to 12 days before hatching. After they hatch, fleas go through several stages before becoming adults. The first stage is the larval stage, which is temperature dependent. Fleas stay as larvae for 24 days in warm weather, or as long as 200 days in cold weather. They tend to burrow in pet bedding or other safe spots where it is dark and warm.

When they are ready, they change into pupae (in a cocoon). This pupal stage can last 5 to 14 days depending on the surrounding conditions. Pupae can survive in their cocoons for up to one year. When the time is right and the pupa knows a host is nearby, it hatches into an adult flea.

When a flea becomes an adult, it looks for a mammal host to provide it with a blood meal. An adult flea starts to feed within 10 seconds of landing on a host.

If you bring home just one adult female flea, in 60 days your home could be overrun by as many as 20,000 fleas! The eggs hatch as quickly as one day, but usually within 12 days of being laid. It is easy to see how quickly a flea infestation problem can spiral out of control.

Fleas Can Survive Without Eating for 2 Weeks

Adult fleas can survive at least two weeks without a blood meal. They are very aggressive feeders and won’t hesitate to feed on people, as well as animals. They are also motivated feeders because they can’t lay eggs unless they eat.

Fleas Can Jump

Fleas are jumping machines. They can jump up to 13 inches, which is like a human jumping 200 times their body length. Think 1,100 feet up in the air for the average five-foot, six-inch person!

This means that fleas can easily jump onto human, pets, and even through screened doors and windows.

Flea Environment Should Also Be Treated During a Flea Infestation

The fastest way to remove flea infestations is to treat all the animals in your household, as well as your home.

Most pet flea medications kill the adult fleas, but what about the flea eggs that fall into the carpet, bedding, floor cracks, etc.? The flea infestation will persist if you only treat the pets and not the home.

A very effective way to get rid of large numbers of flea eggs, larvae, and pupae is to vacuum your carpets, rugs, and floors frequently (two to three times a week), especially the areas where your pet spends most of its time. Immediately after vacuuming, take the vacuum’s bag/canister outside and bag up the waste. If this is not done, the fleas will jump out and back into the house.

Also helpful in killing fleas is regularly washing and drying your pet’s bedding (two to three times a week). The heat will dehydrate and kill the young fleas. 

When you clean your home, always get into the cracks and crevices. Remember, even one missed flea can leave about 20,000 more fleas within 60 days of maturing.

All Pets Are at Risk for Flea Infestations

All pets are susceptible to flea infestations including your house cat, indoor rabbit, guinea pig, etc.  Fleas can “hitchhike” into your home riding on clothing, backpacks, and dogs. Since they also affect wildlife, the eggs and larvae can be found virtually everywhere.

If you live in a warmer part of the country, particularly where there is much humidity such as the Southeast, you will experience a year-round flea problem, more so than people living in cooler, drier areas such as the Northeast. But wherever you live, there will always be fleas waiting to get into your home and start feeding.

Fleas Can Cause Flea Allergies

Fleas may cause flea bite reactions, and even true allergic reactions to the proteins in their saliva. When they feed, they usually regurgitate some saliva into the host, and some animals (and people) are more sensitive to this than others.

Allergic reactions range from small welts and irritations to large, painful sores which can last for days. Even a single flea bite can make an allergic animal miserable. If left untreated, pets may develop severe sores which can become infected and very challenging to cure.

Fleas Transmit Diseases That Impact Humans

Fleas can cause problems not only for animals but also people. The Bubonic Plague was responsible for the deaths of more than 25 million people. In addition, cat scratch fever or murine typhus are among the diseases caused by flea bites.

Fleas Transmit Parasites

Fleas transmit diseases as well as parasites. One of the most common parasites is the tapeworm. It’s futile to give your pet tapeworm medication without treating the fleas because the tapeworm will return quickly if the fleas are still present. In some parts of the country (primarily the Southwest and Alaska), there is a species of tapeworm that can be transmitted to people. 

If Not Treated, Flea Infestations Can Make Pets Extremely Sick

If not treated, severe flea infestations can make your pet gravely ill and may even be fatal. Kittens, puppies, and even adult animals may become severely anemic if exposed to a large number of fleas. Remember that fleas feed by drinking blood, and the more fleas, the more they need to feed.

Fleas transmit disease and parasites, and may cause severe and infected sores for animals that are not treated.

How To Keep Pets Safe from Fleas

Treating and preventing flea infestations has greatly improved over the years. With new and very safe medications that can be used year-round—on almost all animals—pet parents can go a lifetime without ever seeing one flea. Speak to your veterinarian about which products they recommend for your area. All these issues can be avoided by understanding the facts about fleas and flea infestations and with prior planning.

Sandra C. Mitchell, DVM, DABVP


Sandra C. Mitchell, DVM, DABVP


Sandra Mitchell is a 1995 graduate of the New York State College of Veterinary Medicine. Since graduation, she has worked in many fields...

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