Where do fleas lay eggs?

animated gif of cat flea laying an egg in a dogs fur

Fleas — Michael Dryden, DVM, MS, PhD

Img 1 A female cat flea laying an egg in a dog’s haircoat.

Summary

Female fleas lay eggs on their host. On cats, most fleas live around the neck. On dogs, they’re more often found around the hips. Flea eggs aren’t sticky, so they’ll soon fall from the animal’s fur. The eggs accumulate in areas where pets rest, namely carpeting.

Details

Where Eggs are Laid

Fleas are Permanent Ectoparasites

Adult cat fleas are permanent residents of their hosts. They’ll rarely leave of their own choosing. When grooming is restricted, 85% of female and 58% of male fleas will stay on the animal for over 50 days. Few fleas transfer between hosts, even when cats live together. Fleas usually only abandon a host if it’s dead.

Eggs are Laid on the Host

Adult cat fleas feed, mate, and lay eggs directly on their host. This activity continues until they’re dislodged or die. The eggs gets deposited into the pelage of the host animal Img 1.

Where Fleas Live on Dogs & Cats

On cats, most fleas live on the dorsal area, namely the neck and collar. On dogs, they’re more likely to live around the hindquarters. Fleas prefer living in regions which are infrequently groomed by the host. It can be assumed that eggs get laid near these areas as well.

The Eggs Fall Off the Host

Flea Eggs aren’t Sticky

Cat flea eggs have a rounded oval shape. The shell’s surface is smooth. Freshly laid eggs are wet and sticky, so they don’t immediately fall from the host. However, they dry rapidly. And, once dry, the eggs become non-adherent. They’ll then readily fall from the animal, even without grooming.

How Quickly the Eggs Fall

In one study, 60% of flea eggs fell from a cat within two hours of being laid. 65% had dropped off by the fourth hour. Close to 70% were dislodged by the eighth hour. At this point, only 2.3% of the eggs remained on the host. The other 27.7% were believed to be consumed by the cat during grooming.

How quickly the eggs fall depends upon the host’s grooming and movement habits, as well as its hair length. A small percentage of eggs may become lodged in a pet’s fur, especially if the hair coat is dense and dirty.

When fleas bite, saliva is introduced into the wound and causes irritation. The itchy sensation induces scratching, which hastens the speed at which eggs (and feces) fall from the host.

Where the Eggs Fall

Dislodged eggs drop into the environment, both indoors and outdoors. They continually fall, getting distributed anywhere an infested animal can access. A pet’s movement and behavior patterns dictate where the eggs get dispersed. Most get deposited inside of homes, and clumped in areas where pets habitually sleep, rest, and feed.

Flea eggs accumulate in resting sites because oviposition and egg shedding peak at night, when domestic dogs and cats sleep. In addition, cats spend most of their time sleeping, resting, and grooming. They’re only active for 13% of the day. Cats also commonly share preferred resting sites with other cats.

Though there’s a clumped distribution, eggs still get widely dispersed around a host’s movement range. Less than 50% of larvae live in areas where a cat spends 90% of its time, and larvae rarely travel far from where they hatch.

Habitat Requirements

Only the eggs which fall onto substrates with specific habitat requirements will successfully develop. Viable incubation zones aren’t widespread around homes.

Humidity & Temperature

Flea eggs are susceptible to desiccation. To successfully hatch and continue developing, they must fall onto substrates with a warm, humid microclimate. A relative humidity (RH) between 50-92% is optimal for flea eggs. Desiccation occurs below 50% RH. Ambient temperature must be between 50.4°F and 100.4°F (10°C and 38°C) for eggs to survive.

how long does it take flea eggs to hatch

Fig 1 Environmental conditions required for flea eggs to survive, and days until they hatch.

Adult Fecal Blood

Without food, flea larvae will starve to death within three days of hatching. Their primary food source is the feces (flea dirt) of adult fleas. For fleas to successfully develop, eggs must fall into habitats that contain plenty of fecal blood. Flea dirt doesn’t fall from hosts as easy as eggs. It’s typically only dislodged during grooming. So, areas containing both eggs and feces tend to be where hosts groom themselves.

Where Flea Eggs Incubate

Indoors

Carpeted Rooms

In homes, most immature fleas live within carpet fibers. Carpeting creates a near ideal microhabitat for eggs and larvae. The canopy protects them from sunlight, air flow, vacuuming, and insecticides. It also traps food for larvae.

Flea eggs end up concentrated in rooms where pets spend the most time, namely bedrooms and living rooms. Within these rooms, eggs amass in areas where dogs or cats sleep, such as at the side of a bed or sofa.

Common Incubation Zones

The most common places to find flea eggs indoors include: Carpeting, rugs, floorboard cracks, pet bedding, cushions and upholstery, beneath beds and furniture, and dirt floor basements.

Uncommon Incubation Zones

Fleas rarely develop in carpeting that gets a lot of sunlight, or in well-traveled areas like hallways. Few eggs will successfully hatch on wooden floors, and even fewer on tile or linoleum. However, they may develop within the cracks of these floor types.

Outdoors

Outdoor Survival is Rare

Viable habitats are more rare outdoors than indoors. Flea eggs won’t survive in open, sun-exposed areas. They need to be sheltered from fluctuations in weather conditions. Habitats must be shaded and shielded from the wind, with relative humidity exceeding 45% at all times. Grass, for example, isn’t a suitable habitat. In addition, eggs dropped by roaming hosts usually won’t survive, because they are unlikely to fall near flea dirt.

Common Incubation Zones

The most common places to find flea eggs outdoors include: Dog houses, pet shelters, flower beds, gardens, crawl spaces, dense ground cover, vegetation around structures, feral animal nests, and areas where pets go to escape the sun’s heat. For example, animals often seek shade under homes or decks.

References

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Discussion

  • Amy October 7, 2016, 6:23 am

    Can flea larvae lay eggs under the skin of dogs

    • Adam Retzer October 7, 2016, 3:45 pm

      No, flea larvae don’t lay eggs, adult fleas do. And adult fleas don’t lay eggs under the skin of animals. The eggs are laid on the pelage (haircoat). They are non-sticky and fall off within a few hours into the environment, where the nutrients reside that larvae feed on upon hatching.

  • Amy August 16, 2017, 5:08 pm

    Can fleas reproduce in my house if I don’t have pets?

    • Adam Retzer September 28, 2017, 11:38 am

      They shouldn’t be able to in most cases. Cat fleas (C. felis) and dog fleas (C. canis) can’t reproduce on human blood. See our page on this here. However, a more rare species, human fleas (P. irritans) may be able to. Unfortunately, this website doesn’t focus on this species because it isn’t very common.

  • Fleabitten August 29, 2017, 10:45 am

    I need help please!!! I don’t have pets but I have fleas. We moved to our apt almost 2 years ago. I remember seeing a flea or 2 a couple of months after we moved in but I never thought it was a problem. Besides they never bit me before. I would see them jump on my foot when I first come out of the shower. I caught both right away before they bit me and thought there is no problem. Now after almost a year from that incident. I was setting on the carpet with my 3 months old baby and i got bitten. I knew it was fleas, because I saw them. After this they continued bitting me daily. I started vacuuming like crazy, I used baking soda and salt on carpets and vacuumed again. Got a steam cleaning service. Made him steam clean under furniture. Then I realized that they come from the plants outside because the minute I opened my door after the steam cleaning guy was gone, I saw several jumping on my feet and ankles. I had someone cut the plants around my door and spray after. I got flea traps which caught around 6 fleas in 10 days. But the problem is I still get bites and i see them jumping on my feet right next to the trap, so I know the trap doesn’t work and i probably have so many still living in carpets. I vacuum every single day under furniture (the ones that I can move) and spray vinegar in front of my door to prevent new ones from entering. I don’t want to use any chemicals because of my baby. It has been over 3 weeks and every day I find a new flea jumping on me. I am afraid to go out or put my son on the carpet and even afraid to put my feet down. I don’t know why I still have them! And I don’t understand how flea eggs got laid on my carpet?! I don’t believe that all these fleas coming in groups from outside. Please help me I am going crazy and I am scared they would bite my poor baby. Also, my neighbors have cats and there is one cat that comes and used to sit in front of my door. I never let it in and it is supposed to be clean. A couple of my neighbors told me that they get bites entering their apts too. The land lord would not do anything about it. Also some other neighbors complain of having rats in their patios. I never open my patio door though.
    Thank you!

    • Adam Retzer September 28, 2017, 3:33 pm

      Sorry to hear about your troubles. It sounds like you may be dealing with human fleas (P. irritans). This is a somewhat rare species that this site doesn’t focus on it, but the control methods are the same as other fleas. It’s also possible that cat fleas (C. felis) are coming from outdoors. It’s unlikely that the rats are the source, as rodents have their own species of fleas that don’t typically bite people or pets.

      Flea traps are useful for identifying fleas and assessing populations, but they are a poor method of control. Baking soda, salt, and vinegar aren’t proven control methods. There is anecdotal evidence they are effective from online testimonials, but I’ve never read any researched literature that state they provide any noticeable results.

      Please see our page on How to get rid of fleas. Vacuuming is a really effective, chemical-free way to control fleas. However, you may also want to consider applying an insect growth regulator (IGR). IGRs mimic natural insect hormones that control development. Any eggs or larvae that get exposed won’t be able to mature into adults. And IGRs last for 7 months indoors, which is nice for prevention. IGRs are considered safer than traditional insecticides because they specifically target the endocrine system of insects, which are different than mammals. It’s possible to purchase just the IGR concentrate without any other chemicals. For example, Martin’s IGR comes in a good size for indoors. There are also other concentrates available. Look for the ingredients pyriproxyfen (Nylar) or methoprene (Precor).

      • Fleabitten September 28, 2017, 6:05 pm

        Thank you for your reply! I have been patiently waiting for it. I don’t know what kind of fleas are they but I keep seeing them jumping on my feet whenever I go out and I believe they enter on my clothes. Also, I noticed the neighbors cat scratching like crazy in front of my door and apparently my door is her favorite spot. Could I be picking flea eggs when I go out and spread them over my carpet? Also, interestingly we were clear for about 10 days then the flea trap I have inside in front of the door started picking new ones. I learned that my next door neighbors have cat fleas and they are in the process of moving out, could they be spreading fleas around and maybe the fleas are finding their way through my window or door? I don’t get any new bites anymore. It just irritates me that I started catching new ones. My question is, how can I prevent new ones from entering and if I pick eggs on my shoes how to prevent that? I am really paranoid about using any chemicals for my baby. I really appreciate your answer!
        Thanks in advance.

        • Adam Retzer September 28, 2017, 6:40 pm

          It’s possible fleas are coming from your neighbors cats. It sounds quite likely if the cat has fleas and is scratching outside of your door. Fleas will jump onto people if their preferred host isn’t around when they emerge from cocoons. So it’s possible there are fleas developing outside of your door. When they mature and emerge, they jump onto your feet or lower legs, getting brought into your home.

          If the previous assumptions are true, then you are bringing adults into the home, not eggs. The eggs can’t survive without flea feces in the environment, as the hatching larvae require it for nutrition. Flea feces only occurs and drops in the environment when an infested animal is there. So you wouldn’t need to worry about any eggs.

          If they are cat fleas, then they won’t be able to lay eggs or survive without a dog or cat in your home. But they may bite you or members of your family before they perish.

          As far as chemical-free control, try to shake off your shoes and pants before entering your home. This should help dislodge any potentially hitch-hiking fleas. Other than that, keep up a regular vacuuming regimen, especially in rooms where you notice the fleas. You may want to purchase another flea trap or two to place around the home, so you can assess which rooms are the biggest problem.

          • Fleabitten September 29, 2017, 6:34 am

            Thank you for your quick reply 🙂
            I am so relieved that I am not dealing with eggs too. I was confused and didn’t know which stages I was dealing with. It sounds right that they are only the adult fleas I pick from outside. The only trap that catches fleas is the one next to the door. I could see them jumping outside as soon as I open my door. However, I don’t know how they survive the hot sun here in California. Upstairs I had the traps for weeks and they didn’t catch anything. I don’t depend on the traps that much though. We honestly were seriously thinking of moving out because that problem seems to continue and I believe the whole building is infested because that cat is running all over the place dropping flea eggs. We talked to the neighbors to keep their cat in, but she seems to find her way out every day. I still vaccuum every day downstairs and every other day upstairs. I hope it is going to make a difference 🙂
            Thanks again for all your help!

  • Adrienne Szatkowski October 2, 2017, 5:05 pm

    My dog used to go upstairs but hasn’t for many months. I did deposit borax on the carpeting, and have not used the room (my sewing room) for months, either. I went up recently and saw little flea like eggs on my sewing machine brown cabinet around my laptop, etc. I did discover flea eggs on my top sheet when the dog used to sleep there at night. I wonder if the fleas would still be upstairs and lay eggs on my things? Or could it just be the borax I have spread when I used it, etc. IDK: I read borax was toxic and don’t buy it anymore. Just wondering about fleas possibly laying eggs far away from pet on furniture. Thank you.

    • Adam Retzer October 3, 2017, 10:22 am

      The material you found on your cabinet and around your items are most likely not flea eggs. Fleas lay their eggs on their host, but they fall off within a few hours. The only way eggs could’ve gotten there is if they fell from your dog in that location.

      • LR November 19, 2017, 1:59 pm

        I wipe my kitchen cabinets down constantly because of what I am 80% sure are eggs. We have a flea issue, but have controlled it on the dogs. Is it not true that fleas can jump 5 Ft? The substance crumbles in my fingers and turns brown when I submerge in water. Doesn’t that sound like eggs?’
        Thank you

        • LR November 19, 2017, 2:04 pm

          Also: I do not see any jumping on furniture or anywhere so I don’t feel like I am infested, just seem to be finding a lot of signs…………dead adult fleas (from spraying) flea poop and eggs

        • Adam Retzer November 19, 2017, 3:53 pm

          Fleas can only jump to around the height of a human ankle (7.9 inches max). The eggs are a transparent white color. That brown stuff doesn’t sound related to fleas. Flea dirt (poop) appears as a dark substance, but it will turn red when submerged in water or rubbed on wet cloth, because it’s composed largely of host blood.

          • LR November 20, 2017, 4:29 pm

            I really don’t know what is on my counter and cabinets then. I wipe them down and it reappears. The white substance crumbles and turns brown when I submerge in water. Any ideas?

    • LR November 19, 2017, 2:49 pm

      Adrienne, I find the same thing in my kitchen. I wipe the counters and cabinets with dawn dish soap and an hour later I find what I believe to be eggs on both. I am a very clean person and have vacuumed wiped down and sprayed religiously. It is freaking me out

  • mari October 12, 2017, 5:32 pm

    I bought a puppy in September. Had fleas when I got it, owner and I combed puppy with flea comb and she sprayed him with frontline spray. I bought frontline for him that day and applied it to him and my other dog. I have washed bedding, rugs, pill I ws, sprayed furniture and mattress with a product that is supposed to kill all stages of fleas, vacuum like a mad woman, bathed dogs with dawn, rinse with apple cider vinegar, combed with rubbing alcohol as recommended. My dog then got them. Reapplied frontline to both, resprayed, steamcleaned, etc. Found out fleas can become immune to a certain treatment. Vet gave me vectr a 3D6K 6 days ago. Still finding flea eggs on puppy and bedding. Ughhhhhh! Have not seen live fleas for quite awhile. Where the heck are these eggs coming from?

    • Adam Retzer October 17, 2017, 10:33 am

      There are regular studies done to test fleas’ resistance to modern insecticides, like those used in Frontline. There have been no documented cases of resistance outside of labs. I’m not sure where you read that they have become immune to these chemicals, but I’ve never come across an authoritative source. Still, that’s not to say it’s not possible.

      Many claims of resistance are due to pet-owners assuming the flea drops should end an infestation quickly. Unfortunately this isn’t the case. Even with effective treatment, it’ll still take around 8 weeks for an infestation to end. During that time it is normal to see fleas until they completely die out. This is why flea drops often come in at least 3 monthly doses.

      It’s not a good idea to wash with Dawn after applying Frontline or other flea drops. The Dawn is made to remove oil. Flea drops work by incorporating into the dogs’ natural body oils. When you shampoo with Dawn, you will remove a lot of the treatment. Even with milder dog shampoos it’s recommended not bathe pets too often.

      It sounds like you’ve taken all the correct steps to end the infestation. Are you positive they are flea eggs? If you haven’t found any fleas or flea dirt on the dogs, then it does indeed seem strange that you are finding eggs. Sometimes pet dander gets confused for flea eggs. Is this possible?

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