Things You'll Need
Minnows or goldfish
Plastic mesh window screen
Rain barrels are used to collect rainwater from rooftops, which can be used for watering gardens, washing cars or flushing toilets. This method of harvesting rainwater cuts down the cost of water usage in the household and conserves water. However, rain barrels with standing water can also become rich breeding grounds for mosquitoes. There are ways you can keep mosquitoes out of rain barrels and help reduce mosquito breeding sites.
Empty rain barrels every four to six days. Female mosquitoes lay eggs in stagnant water. It only takes seven to 14 days for the egg to emerge into an adult mosquito.
Add mosquito-eating fish into the rain barrels. Minnows or goldfish, for example, are known to eat mosquito larvae. Provide adequate ventilation for the fish inside the barrel, or they'll die.
Use small portions of mosquito dunks. Buy the product from most garden supply stores. Mosquito dunks are bacterial larvicide that kill mosquito larvae. These dunks slowly release an active ingredient, Bacillus thuringiensis (Bt), that kills mosquitoes for 30 days or more. They are safe for your plants and don't harm pets or people.
Cover the rain barrel with fine screening. Screens keep mosquitoes out and prevent them from laying eggs into the water. Secure plastic mesh window screening over your rain barrel's openings. Add cheesecloth on top of the screen as an additional filter.
Have an overflow hole on the rain barrel to keep the water level below the screen. Mosquitoes can breed in the water between the screen and the top of the water surface if the rain barrel is full to the top.
If your rain barrel has an attached hose, put a screen on the end of the hose attached to your overflow. Mosquitoes can enter the rain barrel through the hose. Put a tiny screen onto the overflow fixture, using a hose clamp.
If you're looking for an easy way of keeping mosquitoes out of rain barrels, use mosquito larvicides. Larvicide treatment of breeding habitats helps reduce the adult mosquito population. Simply follow the directions on the product's package, and put the directed amount into the rain barrel where mosquitoes breed.