The Lives Of Fleas – Life Span, Living and Life Cycle

Understanding the life span, the life cycle, and the preferred living space of fleas will really help you get rid of them from your environment. As I am sure you already know, these pests are notoriously well adapted for survival, but once you have read over this guide, you will be better equipped to beat an infestation. Let’s get started!

  1. If you are short on time, click here for a quick summary of this guide.
  2. Can these pests live on humans (in your hair), or travel with you?
  3. Where do these bugs live, and where can you typically find them?
  4. How long can these insects live without a host (before dying)?
  5. The complete life cycle of a flea, and what you can do to stop it.

How long do fleas live (the average adult life span)?

On average, adult fleas usually live for two to three months, provided it has constant access to a meal of animal blood. Of course, this time frame can vary due to different circumstances in its environment. For example, a grooming cat may end the life of a newly hatched flea, or an adult can live for up to a year if living conditions are absolutely perfect.

Varying temperatures also play an important part in determining the life expectancy of a flea, as they are sensitive to extreme heat or cold. Freezing temperatures will spell doom for these insects, and conversely, temperatures of more than 95 degrees Fahrenheit will be too hot for them to handle. Since seventy degrees is ideal for them to thrive, you can reduce their lifespan and their reproductive speed by dropping the temperature in your home to below this threshold.

Humidity can also have an impact on their lifespan, as they need warm weather and lots of moisture in the air to be active and breed. For example, their eggs need around 75 RH (relative humidity) to hatch, and an adult requires about 50 RH to survive. With this in mind, reducing the moisture levels in your home (or in specific rooms) can make a big difference and can reduce the size of repeat infestations.

PRO TIP: Most flea pesticides are effective on the adults, but not all of them contain IGR (Insect Growth Regulators) which will interrupt their life cycle. I highly recommend that you check the various products that are available in your local area for this (it’s usually listed on the bottle), as it will prevent eggs, pupa and larvae from progressing to fully grown adults.

Can fleas live on humans (in hair), or travel with you?

No, fleas don’t live on people. They do bite humans, but these bites are incidental, and usually when we have an infested pooch or kitty living with us. Although any blood meal can keep this pest alive, we are not their preferred host, and feeding on human blood reduces the fertility of females. If you keep getting bitten, it may be that there are no animals for them to feed on, or you are just in the wrong place at the wrong time.

Fleas will not take up residence or lay eggs in your hair, and are designed to live on mammals with densely packed fur. These pests cannot burrow under your skin; if you have heard otherwise, they are probably getting confused with sand fleas (sometimes referred to as chigoe), which are actually crustaceans. Even then, this is extremely rare and only a potential problem in remote, impoverished regions with no medical services.

If they manage to get onto you (and hold on), they can use you as a mode of transport. If you visit a home, a public building, or an outdoor area with an infestation, this may result in them hitching a ride with you into your home. To keep things in perspective, this will not happen every single time, but if you do come into contact with fleas, just remember it is a possibility.

PRO TIP: If you suspect that you may have carried fleas home with you, I recommend that you throw your clothes into a hot cycle wash and take a shower. This will be enough to kill any of these lurking bugs, and provided they didn’t already jump off, this can prevent a potential problem in your living spaces (or on your pets).

Where do fleas live, and where can you typically find them?

Adult fleas love to live in dark, moist and warm locations, and prefer to be anchored beneath the thick fur of mammals, as this provides them with a constant source of food. They don’t limit their hosts to pets and often live on horses, goats, rats, possums, and even bats. They are classified as permanent “ectoparasites“, because they seldom leave once they are attached. This means that your pet can technically host these insects indefinitely, so it is critical to take action as the problem won’t usually go away by itself.

If your dog or cat has a flea problem, you will typically find them all over their body. However, they are usually concentrated behind the neck, around the tail, and under their legs, so check these areas first. You may also find something called flea dirt (their feces), and I recommend taking this seriously as it proves these insects are lurking nearby. A good comb will really help you in this process of discovery.

You can also find fleas in the garden, where they will feed on some of the animals mentioned above (rats, etc.). This means that you don’t have to have pets to have an infestation, and these little pests can make a lovely day outside a very frustrating experience. If you are battling with them outside, I recommend that you try using beneficial nematodes and cedar wood chips in your garden (works great).

PRO TIP: I don’t recommend you spend time trying to find their larvae or eggs, as they are very difficult to find. Another tip, since adult fleas will move towards openings that provide light (window sills, entrances, cracks in concrete, etc. in their attempt to find a host, spend a little extra time to treat these areas regularly, especially if you have a bad infestation.

How long can fleas live without a host (before they die)?

Picture of a host that fleas could live onAn adult flea who have already eaten blood will only live a few days without a host due to starvation. Once feeding regularly, their metabolism changes, and they become dependent on a constant supply of food. The female may die even die within 24 hours if she is in the process of laying eggs, as this expends more energy.

Fleas that have not attached themselves to a host will not have undergone these metabolic changes, and without this blood dependency, they can usually live for up to 15 days without a host. This timeframe allows them to try find a suitable animal (such as your dog or cat), feed on blood, and then start reproducing.

Pre-emerged adults, who have not yet hatched from their extremely resilient cocoons, can enter into a state of dormancy and can survive for over a hundred days! They will lie in wait for the perfect opportunity to hatch, which can be a change in temperature, a rise in humidity, an increase in CO2, or even vibrations caused by a vacuum cleaner.

PRO TIP: With the above in mind, you could move into a new house or apartment where even the previous homeowner didn’t know there was an infestation. Even without pets, environmental changes can result in a sudden, unexpected outbreak. If possible, I recommend that you treat all the carpets in the new house before moving in, especially if they had animals.

The complete flea life cycle, and what you can do to stop it:

Understanding the flea lifecycle is essential, as it can help you get rid of an infestation quicker than usual, stop it repeating over and over again, or even prevent another one from happening in the future. Here is a quick look at the stages, and what you can do about it.

Stage 1: A female will lay eggs after two days, and they are about 0.02 inches (.5mm), slightly translucent, and look like grains of salt.

Stage 2: After two weeks, they hatch into larvae, which look like tiny bristled worms that try to hide from any source of light.

Stage 3: Jump forward another two weeks, the larvae will “cacoon” themselves (pupae stage), and develop into adult fleas.

Stage 4: This is the adult stage of their development, but it will only usually emerge if it knows conditions are suitable for it to thrive.

How to do stop this cycle? Your primary goal is to stop the developing fleas from becoming adults who lay more eggs. This can be done with IGR, or if you want to the natural route, you need to keep the solution (e.g. DE, borax, salt, etc.) down for at least 5-6 weeks. This is key, and since most skip this, many think that DIY solutions just don’t work, which is simply not true. Your second goal is to kill the existing adults, and the good news is that the solutions above will work on them as well. The only exception is your pets and yard, which typically need to be treated separately. I have guides on all of these, and you can also review what each stage looks like here.

A quick summary of this article if you are short on time:

Picture of the full flea life cycle

On average, an adult flea can live for two to three months, but this does require a constant food source. If the living conditions are perfect (humidity, temperature, etc.), it’s life span can be much longer (or very short if it is not).

Humans are not an ideal host for a flea, as it’s adapted to move through a thick coat and lodge itself firmly in hair. Additionally, although they may often bite us, our blood actually reduces the fertility of the females. So although they may travel on us, they will not live (or lay eggs) on any part of our body.

Fleas love dark, warm, humid, and places where there is food. This means that in addition to hiding on your pet, they can often be found in carpets, soft furnishings and in beds. Since they also feed on other warm-blooded animals, it is possible to have an infestation in your yard.

Without a host, an adult flea who has tasted blood in the past will only last a few days. If it has not had a blood meal, it can last for about two weeks before dying. However, a pupa can survive for over 100 days, which can lead to a sudden outbreak where it seemed there wasn’t a problem.

The flea life cycle consists of egg, larvae, pupae, and the adult. Understanding this cycle can be a big help when trying to stop an infestation, and can even help you to prevent one proactively. I recommend that you take a few moments to familiarize yourself with each stage and let me know if you have any questions.

A couple of popular FAQs, and my concluding thoughts:

How long do survive after Frontline? According to the manufacturer of this spot on, fleas will live for about 24 hours after application. Please note that the effectiveness of this product varies on a per-region basis, so try another brand if you do not have good results.

How long can this pest live in a car? If it has not tasted blood, they can live for about three months. However, they are likely to have bitten you, which means if they don’t feed again, they will die in a few days. Note that steam cleaning the interior will kill them instantly.

How long can this insect live without air? This is a strange one, and to be honest, I couldn’t find a direct answer. Suffice to say, however, there are much easier ways to kill a flea without robbing it of oxygen, so rather do that instead of putting them in a zip-lock bag.

Can they survive the washing machine? Using your washing machine is a really effective way of killing fleas, as the adults, the eggs, larvae, and pupae will not survive a hot water cycle. It is not only the heat that will be deadly but also the laundry detergent.

Can you drown a flea in water? Yes, you can, but this will take quite a long time, and they might jump out of whatever container you are using. However, if you add a little bit of regular dish soap to your water, it will usually kill them instantly (tried and tested).

Will these critters die in cold temperatures? Yes, as I have already mentioned in this guide, these insects are susceptible to the cold. If the average temperature (over 24 hours) drops to less than 37F, their population will start to dwindle (in a noticeable way).

Thank you for reading my article, and I hope that it has helped you to understand the life of these blood-sucking critters so that you can take action immediately. I would love to hear from you, so if you have any comments or suggestions, please use the comment section below. 


  1. Avatar M says:

    I have been infested with some strange bug in my hair. Been to doctors and clinics and they say they are not lice. I comb them out by the hundreds and they do bite. I wash my hair several times a day and have tried all the lice treatments on the market both over the counter and perscriptions. No luck with anything.
    They are very tiny little black things. This has been going on for 5 months and I am about to lose it. Any ideas?

    • Natasha Anderson Natasha Anderson says:

      Hi M! Goodness, I would have to see some sort of photo before I can try identify it. However, although I would be happy to help, my advise is to take a visit to your local hospital for assistance, as it sounds pretty serious.

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