Chlorine bleach kills mosquito larvae. It can be added to standing water and sprayed onto items that occasionally collect water, such as bird baths and swimming pool covers. The bleach must contain at least 5.25 percent of the active ingredient, sodium hypochlorite, in order to be effective.
One tablespoon of chlorine bleach is enough to kill mosquito larvae in 50 gallons of standing water. However, a more concentrated mixture of bleach and water in the ratio of 1:1 is recommended for spraying items. Bleach should not be used to kill mosquito larvae in natural ponds and streams, whether on private or public property. A permit and approved larvicide is necessary for this purpose.