Would a first frost kill off all fleas? We have a 10 year old cat that has never been outside. But we now have a gated backyard she will be able to go outside without any fear of losing her.
We get this question quite a bit. A hard freeze will kill most any exposed insect. And if it didn’t kill them, it would at least make it immobile which in turn would contribute to it’s death. And fleas are no different. But will cold weather “cure” a flea problem? No way!
Mother nature has designed insects to be able to withstand the environment in many ways. Even in regions that get freezing cold for several months, at some point if they warm above the freezing point there will be some insects that emerge and get active. That being said, cold weather will no doubt “turn off” most any insect effectively shutting down their internal functions. Sometimes they can rebound in any one calendar year but for most, it will lead to their end.
Since fleas have a short life span anyway (7 days or less), many are dying daily whether it’s cold or not. And flea larvae are even more susceptible to the environment which means the cold will no doubt affect them big time. But as explained in our FLEA CONTROL ARTICLE, there is nothing that can kill a flea pupae so they’ll remain in the yard ready to go. That means the next time it’s warm out they could start hatching thus creating the problem all over again.
And since it only takes one flea outside to cause a major problem inside, the prospect of getting a flea problem inside the home is always present – even in the middle of winter! In other words, if you or your pet went outside on a warm day and got a flea pupae to hatch onto your clothing or skin, you could very well bring it inside and initiate a problem. So too could the cat.
So to answer your question, yes, a good cold night can kill some fleas. But no way will this mean they’re gone for the season and though it will help to reduce local populations, fleas will still be present in some phase ready to prosper once the weather warms again.