Not really. And not ever for Aedes aegypti mosquitoes.

Early last year we published an article in Fisher Park’s newsletter and website focusing on Aedes aegypti, and that information is still there and a good reminder about what you should do as spring and summer arrive. This article is to let you know about things to do right now during the winter season.

Both Culex and Aedes mosquitoes mainly live, breed and bite outside during warmer seasons. Cooler weather slows their metabolism and interrupts breeding, and adult mosquito life cycles end or they die from the cold. But Aedes mosquitoes are capable of living and breeding 100% indoors.


The OC Mosquito and Vector Control District pamphlet passed out with our Winter 2022 newsletter gives a good overview of mosquitoes and how to control them. Their website gives even more information, but it’s the Aedes aegypti we’re focusing on now because they’re the main problem during the winter. View their Aedes section at their website.

Here are some specific things you can do now:

  • Vases with flowers? Make sure to check the water for mosquito larva, and better to just change it every 5 days even if you can’t see anything. Mosquitoes can go from eggs to adults in 5 – 8 days. You don’t want to have indoor mosquito breeding sites all winter.
  • Bathrooms you don’t always use like guest bathrooms or if you’ve been away for awhile? Mosquitoes can breed in shower and sink drains, and even in toilets. Flush toilets and run water through sink and shower drains that aren’t being used. Every 5 days is the safest timeframe but at least once a week. I asked Vector Control about using bleach in these locations to maybe help control mosquitoes and was told that mosquito larva are fairly resistant to bleach. The high concentration of bleach you’d need could damage the plumbing and porcelain, so that probably won’t work. No problem using extra hot water to kill any you don’t wash away.
  • Pet water bowls? Main thing: change the water often. There’s also something else that’s important. Apparently mosquito eggs can stick to the surface of pet water bowls, usually around the waterline. Just dumping and refilling isn’t always enough. Scrubbing with soap will ensure you get rid of mosquito eggs, and changing the water often gets rid of larva before they grow into adults.
  • Christmas tree stands? They usually have a place for water to keep the tree hydrated. The water should be checked and replenished thoughtfully. There’s a balance between letting your tree dry out and having a mosquito breeding location for 2 – 3 weeks under your Christmas tree. There’s no perfect solution but just something to be aware of. By the time you get this newsletter your tree will probably be gone, but hopefully you already saw Vector Control’s Facebook or Nextdoor recommendations. If not, something to think about for the end of 2022.

We will always have a few indoor mosquito control issues 12 months a year, but as the weather gets warmer mosquitoes will also start breeding outside. That’s still where our main mosquito problems will be. We have time to prepare, but some early planning always helps. OC Vector Control’s pamphlet will give you some ideas as will their website. LA Vector Control also has an excellent website. To fill in some potential gaps in the information in both OC and LA Vector Control websites, the information in a previously published Voice of OC article is still valid and relevant. It focuses on Aedes aegypti mosquitoes, maybe the major problem in Southern California since they’re a fairly new arrival and dealing with them presents unique issues.

A few reminders and updates:

  • “Source reduction” or getting rid of places where mosquitoes can breed on your own property, even as small as bottle caps, is still the most effective mosquito control strategy.
  • For places where there will always be water, like water fountains, landscape drains, birdbaths, rain gutters, etc., Bacillus thuringiensis israelensis (BTI) is still the best solution and available as mosquito dunks at most supply stores. Even cheaper in bulk on the internet. Note: BTI is harmless to humans, pets, fish, birds, other animals and most insects except for mosquitoes.
  • No matter how well you keep mosquitoes from breeding on your own property, unless your immediate neighbors are doing the same thing, your neighbors’ mosquitoes will still be biting you. There may be some help for this. The In2Care mosquito control system uses fungus that’s lethal to mosquitoes (my understanding is it’s Beauveria bassiana) to infect mosquitoes that stay alive long enough to infect nearby water sources, like on your neighbors’ property. Currently only available through professional pest control companies, monthly service is fairly expensive. A few Fisher Park neighbors are already using In2Care systems. Some good news: OC Vector Control is testing systems that may become available for direct public purchase and are cheaper than hiring professional pest control companies.
  • There are pesticides that can kill every insect on your property, and also ones that focus on killing caterpillars, including the ones that turn into butterflies. There’s also a non-toxic garlic based product that works by repelling insects from your yard, including mosquitoes. It’s made by a company based in Glendale, California and at least one neighbor is already using it successfully.