Prevent mosquitos from hatching in rainwater barrels

Mosquitos. What should you put in standing water to prevent mosquitoes? Can you use goldfish against mosquitos in water tanks? How do you stop mosquitos from multiplying in a water tank? In which other parts of the garden could mosquitos hatch? Do mosquito dunks really work? Can a mesh or netting prevent mosquitos to grow in standing water? How do I keep my buckets with water mosquito-free?

How do you counteract mosquito breeding in water tanks?

Mosquitos in water
Mosquitos in water

As the world runs out of freshwater it becomes more and more important for everyone to save water and collect rainwater. The ever-growing eco-friendly attitude promotes this trend but it also creates a major problem – mosquitos. Open water containers are a dream come true for mosquitos. Since they can lay a hundred eggs at a time and their lifecycle is short (8-10 days), this means high turnover between mosquito generations and you will soon have an explosion of these flying suckers literally within days!

A single mosquito can lay thousands of eggs during its short lifespan!

Luckily there are many quick and easy tricks you can apply to stop the mosquitos from completing their lifecycle.

No mosquitos thanks!
How to stop mosquitos?

Rainwater barrels

Rainwater barrel
Rainwater barrel with mosquitos

The harvesting of rain in large containers or barrels is an eco-friendly process as it brings along multiple benefits. It reduces the runoff, conserves water, and benefits the plants and soil in your garden. However, your rain barrels can offer a breeding ground to the mosquitoes, leading to health risks and even hefty fines. You surely will not like to have such guests, so here are a few prevention guidelines to keep your rain barrels free of mosquitoes and their larvae (wigglers). Here please keep in mind that rainwater is not fit for human consumption even if mosquito-free, so never drink rainwater. 

Mesh screen 

Mesh screen agains mosquitos
Mesh screen against mosquitos

Using covered barrels is the best and most effective way to keep your rain barrels mosquito-free, potentially the most problematic insects of rainwater. Add a single or double-layered mesh screen on top of the barrel and make sure the mesh’s holes are small enough so that the mosquitoes could not slip in. A mosquito-proof screen for rain barrels is a quick fix and it will not cost you a fortune. You can get it from any hardware store. Secure the mesh by using wire or string so that you do not leave any slits or gaps for the mosquitoes if there is an opening on the side like the overflow port cover it also. We recommend a double layer netting on top of each other. Examine the mesh regularly and replace it if it gets damaged or ripped.

Keep barrel clean and working

Dirty rainwater barrel
Dirty rainwater barrel

It will be useful to remove any debris or other materials like leaves or sticks, which you may see at the top or in the barrel. Make a regular habit of emptying the barrel after a fixed period. Examine the barrel for any leakage or cracks. You can apply a silicone sealant if you find any. Use or remove the collected water as soon as possible. Do not let it stand for a long time. It will be useful if you keep your barrel dry between the rain events. Do not let the water overflow above the screen or collect on the lid. Check the water for larvae as often as you can by scooping out water in a white cup. Larvae will be visible in the white background as black or brown wavy lines. If you find larvae spawning in the water, dump all the water immediately at a far place away from your garden and other people and animals preferably in well-draining soil. This will kill all the mosquito larvae. After a certain period, wash the barrel using a scrub pad and warm soapy water. This will remove any mosquito eggs if attached to the walls of the barrel.

Clean rainwater barrel
Clean standing water barrel

Use the rainwater as soon as possible

Don’t let it stand for more than a week after the latest rainfall. Because this is the average lifecycle time it takes for a mosquito laying eggs to discovering new “mini draculas” emerge again.

Use rainwater quickly
Use rainwater quickly!

Avoid Decorative barrel tops

Some barrels have a decorative top with curved surfaces and spaces where water can pool. Remove this water because even this water can act as a medium for mosquito breeding. However, it is better to select a barrel with a smooth top that doesn’t collect small pools of standing water.

Plant friendly insecticide

Bacteria can eat mosquito larvae

Mosquito dunks are commercially available, which act as an insecticide killing the pesky mosquitoes but do no harm to your plants and other wildlife. It contains a soil bacterium, namely Bacillus thuringiensis israelensis (BTI), which is toxic to mosquito larvae. You can easily find it at your garden supply store.

Does Mosquito dunk really work?

Do follow the instructions of the manufacturer as to how and when to use the product. The product works by releasing bacteria slowly in the water when it is getting dissolved and efficiently controls mosquito breeding.

Dish soap

Soap in rainwater barrel to prevent mosquitos
Soap in rainwater barrel to prevent mosquitos

Adding a tablespoon of environment-safe dish wash liquid may do the job as it will create a thin protective layer on the surface of the water. Reduce the surface tension of water and prevent mosquitoes from laying eggs. Insecticidal soaps are also available that help to control these pests.  Only one milliliter (ml) of the solvent is enough in a gallon of water to kill mosquito larvae within a day.

Support wildlife habitat

Natural predators of mosquitoes can do the job for you and be a great help. Bats, swallows and dragonflies can feast on your problem makers, so providing an environment for this wildlife may solve your problem.

Vegetable oil

Pouring a cup or two of cooking oil in the barrel can also help to keep your container mosquito-free. The oil will form a thin layer on top of the water, which will not allow oxygen to enter the water. If larvae are present inside the water, they will suffocate and die. Larvae feed on microorganisms in the water.


Only one or two goldfish are enough in the barrel to get rid of any mosquito eggs or larvae if they get to hatch. Moreover, their poop can also provide some extra nitrogen to the plants when you water them with this water. But remember to shift the fish inside before the frost. A viable alternative to goldfish is the mosquitofish which, as you might have anticipated, eats mosquito larvae among other things. It is the most used fish for natural volume control of mosquitos.

Apple cider vinegar

Among your household products, you can use apple cider vinegar to kill the mosquito larvae. It is essential to use it in the right concentration. The vinegar to water ratio must be 15:85 for effective action. At lower vinegar levels, you will not be able to get rid of your problem, so be careful in using the appropriate amount of vinegar.

How do you stop mosquitos?

Investigate other parts of your garden too

Have you thought about other parts of your garden where mosquitos could hatch?
In which other parts of the garden could mosquitos hatch?

Maybe your mosquito problem doesn’t come from the buckets or water containers at all? There are many other places in your garden where mosquitos will thrive and replicate. This guide will help you eliminate other sources of the mosquito problem. You can also try this comprehensive guide to get rid of mosquitos, maybe you will find a solution not mentioned in this article.

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