How long do flea eggs live for?

Summary

In homes, flea eggs live for 2 to 3 days before hatching. Most eggs and larvae live in carpeting. The microclimate within the carpet fibers is near ideal for developing fleas. As a result, the incubation period is brief.

Fig 1 Days it takes (y-axis) for 50% of flea eggs to hatch at different ambient temperatures (x-axis) while relative humidity is held constant at 75%.

Details

How Long it Takes Flea Eggs to Hatch

Ambient temperature is the primary factor which governs how quickly flea eggs incubate. However, relative humidity (RH) is important for their survival.

Flea eggs develop in sheltered microhabitats. These areas have their own microclimate, where humidity and temperature are moderated. Thus, conditions in the surrounding environment are of little significance.

how long does it take flea eggs to hatch

Fig 2 Environmental conditions required for flea eggs to survive, and days until they hatch.

In Homes

Most flea eggs get deposited indoors within carpeted rooms. Modern carpeting creates a favorable environment for incubating eggs. In a home setting, flea eggs typically hatch into larvae within two to three days of being laid.

In Ideal Conditions

Flea eggs develop rapidly in warm, humid environments. They’ll hatch within 1.5 days when conditions are optimal Fig 1. Ideal conditions occurs at temperatures near 89.6°F (32°C), and humidity between 75-92%. Nearly all eggs will survive and hatch in these conditions.

In Poor Conditions

As temperature is lowered, the eggs take progressively longer to develop. In poor conditions, it can take 8-12 days for flea eggs to hatch.

Failure to Hatch

Cat flea eggs can’t withstand large fluctuations in temperature or humidity. For example, the eggs will die outdoors during the winter due to the cold, arid air. They don’t go dormant.

Extreme Dryness

In dry conditions, flea eggs will desiccate without hatching. A relative humidity below 50% is often lethal. While 80% of flea eggs survive when RH exceeds 50%. In one study, the eggs survived in as low as 33% RH Fig 3. However, hatching larvae quickly died in these environments, as they’re even more vulnerable to desiccating than eggs.

60°F
80°F
95°F

Fig 3 Percent of flea eggs that survive (y-axis) throughout different increments of relative humidity (x-axis), at three constant ambient temperatures.

Extreme Cold

Cold temperatures are lethal to flea eggs. The lowest temperature they can survive, hatch, and continue developing at is 55.4°F (13°C). Eggs hatch after 12 days at 50.4°F (10°C), but first instar larvae die within 10 days. Flea eggs completely fail to develop below 46.4°F (8°C) Fig 4.

46.4°F
37.4°F
30.2°F

Fig 4 Percent of eggs that survive (y-axis) at three different ambient temperatures across 10 days (x-axis).

Extreme Heat

At the other extreme, flea eggs can’t survive when continuously exposed to any temperature above 100.4°F (38°C). They’ll survive and hatch in 1.5 days at 95°F (35°C). However, this temperature is still too hot for fleas to fully mature into adults.

Higher temperatures require a higher humidity to prevent eggs from desiccating. When exposed to 95°F (35°C), the eggs die at any RH below 75%. Fully saturated air is also lethal at this temperature due to heat accumulating within the eggs. Even at the optimal RH of 75%, only 40% of eggs hatch.

References

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Discussion

  • danna September 16, 2016, 11:46 pm

    I’ve fleaed my cat 2 days ago and im finding the dead fleas on the floor, does this mean I’ve got rod of them? I’ve cleaned carpets bedding etc

    • Adam Retzer September 17, 2016, 12:19 pm

      It doesn’t necessarily mean you’ve completely ended the infestation. However, it does mean the treatments you’ve employed are killing the adult stages, which is a good sign.

  • Bonnie December 11, 2016, 8:13 pm

    I recently found fleas on our dog. I immediately gave him a bath picked off all the fleas that I could find and gave him bravecto. It’s been 3 days and I have not seen any adult fleas on him. Since I found them I have vacuumed everyday. I have washed all of our linens in hot water and dried on hot heat. Once they are dry I have been bagging them and throwing the bad outside. The temperature outside has been 30°F or colder. We have an exterminator coming as well. We have not physically seen any fleas in the house but my question is with everything I am doing, are my chances decent of getting rid of them faster? Everyone says it’s a 3 month long ordeal??

    • Adam Retzer December 12, 2016, 4:47 pm

      It sounds like you’re taking all the correct actions. The Bravecto should kill newly emerging adults as they jump onto the dog, so they can’t lay any eggs. Thus, as long as the dog is treated, there will be no new generation of fleas. Unfortunately, the bulk of infestations are immature stages living in the environment.

      Vacuuming and spraying the premises with an insect growth regulator are the best ways to speed up the eradication process. However, larvae seek out dark areas and are often developing at the base of carpets. Insecticide treatments can’t penetrate to the depths where many pre-adult stages live. Vacuuming has limited success at removing them as well. Before the infestation ends, you’ll have to wait for these stages to complete their life cycle, emerge as adults, and then die. Usually it takes around 8 weeks to completely eradicate fleas, sometimes longer. This is why flea treatments for pets must continue for months. If a female emerges and finds an untreated host, she’ll begin laying eggs within two days.

      Vacuuming is important because it forces cocooned adults to emerge. When they sense the heat and pressure produced by the vacuum cleaner, they think a host is resting on their cocoon. Thus, they rapidly emerge. Without any host cues, the cocooned adults can stay in a quiescent pre-emerged state for up 5 months.

      Though your infestation sounds mild, it probably won’t be completely ended much sooner than moderate infestations. Even a few fleas surviving in the environment could continue the infestation if they gain access to an untreated animal. To good news is you won’t see as many fleas, and won’t have to deal with as many bites.

  • Ro October 29, 2017, 1:30 am

    Had house treated for fleas by council – great job but I found what I believe is flea eggs in my hair – treated them with vinegar then bicarbonate of soda and now when I comb hair with fine comb there is virtually no eggs there. However I have found my eyebrows and lashes itchy and there are little hard round things that I can pick off – could this be eggs developing into next stage. The eggs looked like odd shaped dandruff – these look very different.

    • Adam Retzer October 31, 2017, 12:36 pm

      Ro, what you are finding doesn’t sound characteristic of fleas. Fleas don’t lay eggs in human hair, eyebrows, or lashes. I’d recommend seeing a physician so they can diagnose whatever it is in person.

      • Tracy August 12, 2018, 9:03 am

        I’ve flead my dog with front line 4 days ago n there is still black eggs on him I’ve done all the house I’ve tryed a nit comb not coming off what shall I do

        • Adam Retzer August 13, 2018, 1:41 pm

          Flea eggs are white. Flea dirt (feces) is black. Or more accurately, it’s dark red, as it’s composed of dried host blood. To be sure it is flea dirt, you can take some of the dark specks and place them in water, or rub them on damp cloth. They should reconstitute into blood when moistened, smearing into a red color. If they don’t, then the black specks are unrelated to fleas.

          Flea infestations won’t end immediately after treatment. It will take around 8 weeks. This is because 95-99% of the population consists of eggs, larvae, and pupae living in the environment. Once proper treatment is in place, there should be no new generation fleas, but the current generation needs to mature, emerge as adults, and die. So, it’s common to continue seeing adult fleas for a while. They may jump onto your treated dog and feed and defecate, resulting in flea dirt on the dog. However, the insecticide in Frontline will kill them before they have a chance to mate and lay eggs.

          Speeding up the eradication process can be done by vacuuming regularly, and by applying an insect growth regulator to the environment.

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