Do fleas die in the winter?

Summary

Cat fleas die outdoors in winter. Frost or snow kills fleas. No life stage can survive in freezing temperatures for extended periods. However, adult can stay alive on their warm-blooded hosts, and immature stages can develop in homes or the freeze-protected dens of wildlife. Cat fleas don’t hibernate, despite what some sources claim.

FleaScience

Img 1 Environmental conditions needed for all life stages of the cat flea to survive.

Details

Winter Survival

Fleas Survive Year-Round

Small populations of fleas can be found on domestic and feral animals year-round, even during the coldest months. However, it’s rare for new infestations to begin on dogs and cats during winter. Outdoors, developing fleas can’t survive the cold, arid conditions in most temperate zones. Even in California, few fleas are found from January to April.

Some geographic locations have warm, humid climates year-round. In southern Florida, for instance, fleas will continue thriving outdoors through the winter months of November to March.

Don’t Stop Treatments in Winter

The changing of the seasons won’t end a current flea infestation. Stopping flea treatments early when the cool months set in is a common cause of reinfestation.

How Fleas Overwinter

No flea stage can survive in near-freezing temperatures for extended periods Img 1. However, some fleas won’t get subjected to extreme cold. Adults can survive on warm-bodied hosts, such as dogs, cats, and raccoons Img 2. Fleas can also live year-round if their host lives in a warmed shelter. For example, fleas will survive in heated homes, where, consequently, most domestic infestations occur. The frost-protected dens of wild animals can also keep immature fleas alive during winter.

do fleas go away in the winter

Michelle Bender

Img 2 Raccoons are active in the winter and fleas can survive on their warm bodies.

Fleas don’t Hibernate

Fleas don’t have a true diapause stage. They don’t hibernate or go dormant to overwinter. Adults can enter a quiescent (inactive) state within their cocoon for up to 5 months, but temperatures below 37.4°F (3°C) kill them. Still, pre-emerged adults can survive winters in slightly warmed or insulated structures (e.g. crawl spaces), and then emerge in spring when conditions are better. They may also live through short, mild winters outdoors.

Cold Temperatures Kill Fleas

Adult Fleas

Adult fleas die in temperatures below freezing Fig 2. Death occurs within five days at 30.2°F (-1°C). Within 24 hours, 20% of emerged adults and 72% of pre-emerged adults will die. They’ll survive longer above freezing (37.4°F), but still ultimately die within 10 days.

46.4°F
37.4°F
30.2°F

Fig 2 Percent of emerged adult fleas that survive (y-axis) across 40 days (x-axis).

When temperatures rise above 46.4°F (8°C), nearly half of emerged adults stay alive for 20 days. However, immature stages can’t survive in these temperatures.

Flea Eggs

Flea eggs die outdoors during winter. They don’t go dormant. The eggs can only survive at or above 55.4°F (13°C). At this temperature, 50% of flea eggs hatch within six days.

Flea eggs hatch in 12 days at 50.4°F (10°C), but the larvae will quickly die. At 46.4°F (8°C), nearly half of the eggs are killed in a day, 65% die by day five, and there’s a complete kill by day ten Fig 3. At 37.4°F (3°C), 65% of the flea eggs die within a day. Survival isn’t possible in subfreezing temperatures.

46.4°F
37.4°F
30.2°F

Fig 3 Percent of eggs that survive (y-axis) across 10 days (x-axis).

Flea Larvae

The larval stage is most susceptible to cold conditions. The low-end extreme occurs at 55.4°F (13°C). Flea larvae die within 10 days of hatching at 50°F (10°C).

Another study found similar results. 59°F (15°C) was the low-end extreme. At 46.4°F (8°C), 65% of the larvae died within 10 days, and 100% by day 20. At 37.4°F (3°C), 37% of the larvae died in a day, and none lived past day five days.

References

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Discussion

  • Lisa Voss December 18, 2016, 8:00 am

    I am battling a flea infestation that I inherited from the previous tenants of my apartment. I don’t have pets, but they had a cat. I have had great success following your instructions (spraying, vacuuming, steam cleaning, laundering bedding and clothes) However, I have a foam mattress pad that I don’t know what to do with. I can’t expose it to high temperatures, and I can’t vacuum it because of it’s texture. It’s below freezing every night now where I live. Can I leave it outside in a plastic bag for 5-10 days ? Will that kill any possible fleas ? I don’t know that it was infested, but I don’t want to take any chances. Any other ways to de-flea a foam mattress pad ?

    • Adam Retzer December 18, 2016, 6:14 pm

      Lisa, I’m glad you’ve been successful with controlling the fleas. Yes, leaving the mattress pad outside in a bag during freezing temperatures for 5-10 days will kill any potential fleas there. Most will die within 24 hours. I can’t think of other ways to de-flea the pad that would be easier and more effective than your proposed method. Try to eliminate air from the bag, so it isn’t insulated. And try to keep as much of the pad unfolded and unrolled as possible, again so parts aren’t insulated from the cold.

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