# Will chlorine bleach serve as a "poor man's mosquito larvacide"? If not, What? **URL:** \ **Category:** Factual Questions\ **Created:** [May 26, 2006, 4:44pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335 "2006-05-26T16:44:23Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![stuyguy](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@stuyguy](https://boards.straightdope.com/u/stuyguy)\ **Post date:** [May 26, 2006, 4:44pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/1 "2006-05-26T16:44:23Z")
I have a small tub that fills with rainwater after every downpour. I fear it will attract larvae-laying mosquitos, but it’s a huge pain in the butt to drain. I want something that I can throw in there to kill any larvae that may appear in between drainings. Will chlorine bleach do the trick? If not, is there some other simple, cheap household product that will do the job? I expect to put a permanent end to this situation in the near future so I’m not really interested in buying something new or specialized for this problem. Thanks all. ---
**Author:** ![CrankyAsAnOldMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crankyasanoldman/32/11670_2.png) [@CrankyAsAnOldMan](https://boards.straightdope.com/u/CrankyAsAnOldMan)\ **Post date:** [May 26, 2006, 4:48pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/2 "2006-05-26T16:48:26Z")
> [@stuyguy](#): > > Will chlorine bleach do the trick? I know from experience that it will. However, there may be reasons why you wouldn’t want to do this. I’ll leave it to others to answer that angle. ---
**Author:** ![MLS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MLS](https://boards.straightdope.com/u/MLS)\ **Post date:** [May 26, 2006, 4:53pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/3 "2006-05-26T16:53:56Z")
Why not cover the tub? What’s it there for anyway? ---
**Author:** ![Will\_Repair](https://avatars.discourse-cdn.com/v4/letter/w/a698b9/32.png) [@Will\_Repair](https://boards.straightdope.com/u/Will_Repair)\ **Post date:** [May 26, 2006, 4:55pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/4 "2006-05-26T16:55:21Z")
Oil works. It’s lighter than water, rises to the top and suffocates the larva. ---
**Author:** ![rabbit](https://avatars.discourse-cdn.com/v4/letter/r/919ad9/32.png) [@rabbit](https://boards.straightdope.com/u/rabbit)\ **Post date:** [May 26, 2006, 5:06pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/5 "2006-05-26T17:06:32Z")
Use biological control like mosquito dunks. It’s a bacteria that kills mosquito larvae. Very useful. I had several bodies of water (2 ponds and 3 other pots serving as mini ponds) all perfect for mosquito breeding. Worked great for me. Here’s a link [linky link](http://www.bugspray.com/catalog/products/page336.html) as an example. I’ve found some variation of the same product pretty much every garden center that sells pond supplies. Not expensive at all really and one container (I bought it in powder form) lasts a long time. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [May 26, 2006, 6:09pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/6 "2006-05-26T18:09:35Z")
> [@Will Repair](#): > > Oil works. It’s lighter than water, rises to the top and suffocates the larva. Ditto. Put a cup or so of cooking oil in there. That will stop them. ---
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [May 26, 2006, 6:40pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/7 "2006-05-26T18:40:50Z")
Yes, oil works, but it leaves . . . an oily mess. Bleach works fine, plus will keep algae down. It’s also very unstable in water and will dissipate pretty quickly, so you’ll need to do it with some frequency. Or you could put a guppy or two in there. ---
**Author:** ![capybara](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/capybara/32/202_2.png) [@capybara](https://boards.straightdope.com/u/capybara)\ **Post date:** [May 26, 2006, 7:16pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/8 "2006-05-26T19:16:47Z")
Yeah, I was thinking goldfish. Why do you have a tub collecting water? ---
**Author:** ![Khadaji](https://avatars.discourse-cdn.com/v4/letter/k/9e8a1a/32.png) [@Khadaji](https://boards.straightdope.com/u/Khadaji)\ **Post date:** [May 26, 2006, 7:34pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/9 "2006-05-26T19:34:07Z")
How about a frog? I have a little fountain in my front yard that hosts a frog. I will probably get the dunks, because they say they won’t hurt other wild life, but I was wondering if a frog will feast on those nasty little critters. ---
**Author:** ![Rhubarb](https://avatars.discourse-cdn.com/v4/letter/r/59ef9b/32.png) [@Rhubarb](https://boards.straightdope.com/u/Rhubarb)\ **Post date:** [May 26, 2006, 11:28pm UTC](https://boards.straightdope.com/t/will-chlorine-bleach-serve-as-a-poor-mans-mosquito-larvacide-if-not-what/358335/10 "2006-05-26T23:28:53Z")
> [@CynicalGabe](#): > > Ditto. Put a cup or so of cooking oil in there. That will stop them. The most common anti-mosquito treatment for standing water is mineral oil, rather than cooking oil. The cooking oil will doubtless work as well, but it is a food for many different organisms and will probably grow something nasty in your tub in addition to attracting ants and dogs.