Mosquitoes and Rain Barrels
The threat of mosquito infestation is a real concern for those homeowners who use rain barrels as a means of water conservation. Mosquitoes like to like lay eggs around standing and stagnant water. Many rain barrels are manufactured with screened lids that deny mosquitoes access to the stored water.
Making Your Own Screened Lid
If your rainbarrel doesn’t have a screened lid, you can easily fabricate your own. I purchased a roll of 36 inch wide flexible screening from my local Lowes’ store. I also purchased some of those small/short tie downs that come in a pack. I then cut the screen into 3 sections to cover the top of my 3 rain barrels – with a 24 inch diameter at the top; and I cut some twine I had around the house into 3 pieces less than 75 inches long. (Remember the old formula for Circumference from high school – C = Pi x D (3.14….. x 24?) I then tied both ends of the string to the ends of the tie-down with a slip knot. I then used this “elastic” sting to hold the flexible screen over the top of
the rain barrel.
However, having a mosquito-proof lid on your rain barrel is not the only precaution you can take. Below is a list of additional measures that will prevent mosquitoes from breeding in and around your rain barrel.
Downspout diverters are devices that allow you to either direct water into your gutter rain barrel or to your normal drain system. If you have a downspout diverter, simply close the gate when the water barrel is full. If you don’t own a rain barrel diverter, install an overflow device on your rain water barrel. A PVC pipe or overflow hose can carry water to away from your foundation and prevent excess water from pooling around your rain barrel.
Clean Filters. Keep all barrel filters and pre-filters clean and free of moisture-retaining debris.
Clean all gutters and downspouts. Leaves, twigs, seeds, and other organic matter will create a water dam in which mosquito larvae can grow.
Perform regular inspections of your system to make sure that there are no cracks or leaks, and that all fittings and seals around the valves are intact.
Mosquito dunks are time-release tablets that contain a bacterial agent which kills mosquito larvae, but does not affect people, animals, or plants.
Vegetable Oil.To keep mosquitoes from laying their eggs (or prevent eggs from hatching) it is recommend that you put a tablespoon of vegetable oil in the rain barrel. This creates an oil slick, not harmful to people, pets, plants, etc.
Next Best Solution to Screened Lid
I like the screen solution best for protecting the water in the rain barrel, because it’s a one-time fix that requires no periodic updates. However, if you are not able to use a screen to prevent mosquitoes from laying their eggs in your rainbarrel, do you want to know the best mosquito control I have found that works consistently year after year? The “mosquito dunk” mentioned above! And it’s a “natural” solution! You can obtain a pack of “Mosquito Control Rings” from your local gardening or home improvement store. They look like little gray donuts under shrink wrap attached to cardboard, and they’re usually tucked in among all the insecticides. What are the rings? They are a dried, crumbly “biscuit” that “comes alive” when immersed in water. The rings are actually a naturally occurring bacterium — Bt ‘Israelensis’ — which thrives on mosquito larvae. They release slowly over time, and although the package says to replace them every month, I’ve found one ring can keep a small pond mosquito free for 6-8 weeks.
By taking these precautions, you will have done three things to reduce mosquito breeding:
1) You’ll have prevented moist areas from developing in your gutters and downspouts;
2) You’ll have properly protected your rain barrels from access by breeding mosquitoes and/or prevented the mosquito larvae from hatching; and
(3) You’ll have prevented standing water from accumulating – which often results from a heavy rain-fall – and becoming a breeding area for mosquitoes.