How To Kill Mosquitoes And Their Larvae In Water?


According to the World Health Organization, mosquitoes are vectors for many diseases including malaria, dengue fever and zika virus. Mosquitoes can lay about 400 eggs in water at once and can quickly turn into an infestation. It’s not enough to hate them, you also need to know how to kill them and stop them from coming back.

Mosquitoes can be killed in water and prevented from laying more eggs using methoprene granules, mosquito dunks or bits, mineral oil, vinegar, soap, cinnamon oil, kerosene, paraffin oil, or chlorine. Targeting the mosquito larvae is easier than killing adult females and can stop the cycle of a mosquito infestation.

In this post we cover how to kill mosquitoes in various water bodies, including water tanks, barrels, fountains, stagnant water, and plant water. We’ll also cover how to prevent them from living around your home, and provide details on both chemical and natural ways of killing mosquitoes and their larvae.

Before we dive into the details of mosquito-killing techniques, let’s talk about these insects and how and where they survive and thrive.

Brief insight into the mosquito life cycle

Mosquitoes love and survive in areas with stagnant, standing water. Their survival and breeding rate gets worse if it’s summertime and there’s a lot of encouraging vegetation and microbial growth around.

Mosquitoes have four stages in their life cycle: the eggs, larvae, pupae, and the adult.

Female adults are capable of laying up to 400 eggs at a time. They prefer to do this on the surface of shallow water, and according to the CDC, they prefer water collected in man-made vessels.

To growth from an egg to an adult mosquito takes about two weeks, after which the female breeds again and the cycle continues.

This implies that, if not carefully managed, anyone could have a full mosquito infestation within a month. You’ll know that you have a mosquito problem if:

You find the adults flying around the surface of any water bodies on your property – you’ll probably also start noticing them bit you.

You can see pin-like structures wriggling just near the surface of your water tank, fountain, or any other water vessel. These are mosquito larvae.

You may notice floating egg rafts on the surface of water around you.

Mosquito egg rafts are white when first laid but turn a dark brownish color in 12-24 hours and are roughly 1/4 inch (6 mm) long and 1/8 inch (3 mm) wide.

Now that you know them, what they look like and how they breed, you can learn how to get rid of them effectively.

How to kill mosquitoes in a water tank or barrel

Water tanks and barrels are used as a water storage unit for different purposes. Yours could be for drinking, irrigation, fire emergencies, food processing and production, livestock care, or for some other purpose. Most of these reasons are in one way or another connected to human and animal health, so ideally you don’t want any form of chemical contamination from killing any mosquitoes.

If you notice mosquitoes in your water tank, barrel or any large storage vessel, the safest way to kill the mosquitoes is to disinfect it completely.

For thorough disinfection, the WHO recommends that you:

  1. Discard the infected water first. If you are planning to use insecticides or larvicides to treat the water, there is no real way to make it suitable for consumption, so you are going to have to empty it anyway.
  2. Next step is to SCRUB the inner (and outer) parts of the tank. This is necessary to ensure you’re getting rid of any eggs that have adhered to the edges of the tank with hopes of hatching into larvae under better conditions. This can be done with a stiff brush or pressure washer, detergent and hot water.
  3. Refill the washed tank and disinfect with chlorine.
    • The quantity of chlorine used will depend on the volume of the tank; 7 pounds of granular chlorine for every 10 gallons of water will do the trick (or 80 g of granular chlorine per liter of water).
    • This is allowed to stand for 24 hours for better results.
  4. Run the chlorinated water through the hose, pumps and every valve to ensure that any residual egg raft or larvae colony is destroyed.
  5. Refill the tank with clean water and allow it to stand for about 30 minutes.
    • If it’s a small tank or barrel, discard this water and refill again.
    • For large storage tanks, just fill once.

After this final rinsing, you can be sure that you’ve killed all mosquitoes in any stage of their life cycle. You can now re-seal the tank properly to prevent any further infestation.

Check for entry points

It’s always a good idea to check for any corrosion, holes and leaks while washing, so you can fix them before the refill.

Water tanks and water barrels can easily become a breeding ground for mosquitoes if the females can find a point of entry.

The most likely entry points include the:

  • Damaged inlet and outlet mesh and strainers
  • around the edge of inspection points (such as the strainer)
  • Pipes that feed directly into the tank without passing through a mesh screen first
  • Physically damaged or corroded parts of the tank itself.

Also, mosquito eggs laid in ponded water areas in roof gutters and can make their way into the rainwater tank. So, gutters should be regularly inspected for ponding water and to remove debris.

How to kill mosquitoes in a water fountain

Fountains and water features are beautiful additions to your garden or compound but, if not managed well, can quickly become a breeding ground for mosquitoes.

To kill mosquitoes in a water fountain, you need to first stop them from breeding and then stop the already present larvae from maturing.

Keep the fountain environment clean

This means removing all sorts of vegetation around that could serve as a source of nutrients to the larvae. If the larvae can’t feed, they will die within hours, or at most, days.

Use larvicides

Methoprene granules such as Altosid Pro-G Mosquito Larvicide by Zoecon, and mosquito dunks are the most effective chemicals against mosquito larvae in water. You can buy both of these larvicides on Amazon and you’ll find details about how to apply them in this post here.

Keep the water deep

Mosquitoes prefer shallow water to deep water. Deep water that is two to three feet in depth is unattractive enough to prevent mosquitoes from breeding in your fountain. 

Add bubblers or water wigglers

This is a fancy way of saying, keep the water moving.

Mosquitoes will not breed on moving water since standing water is their preferred habitat. So, if you can keep your fountain water in motion with a water bubbler or water wriggler from Amazon, be rest assured that mosquitoes won’t breed on it and any larvae present will die of suffocation.

How to kill mosquitoes in stagnant water

Stagnant water refers to any water body that is standing, not flowing and not actively circulating. Common areas around the home that can develop stagnant water include:

  • Toys left outside
  • Birth baths and fountains
  • Fish or frog ponds
  • Pet bowls
  • Discarded tires
  • Buckets
  • Gutters with pooling water
  • Bromeliad plants
  • The top of water tanks or barrels
  • Pool covers and poorly maintained pools
  • Puddles
  • Palm fronds
  • Leaves and debris. 

The easiest way to eliminate mosquitoes from standing water is to get rid of the standing water. This destroys a potential breeding ground for mosquitoes and kills the already existing larvae since they can’t survive without water. 

You should also make a habit of washing or cleaning any containers that hold water, especially after it rains.

Remember how the adult mosquitoes prefer to breed in man-made containers?

That’s because their eggs can easily stick to the containers through a dry period for about eight months, and the second they get water, they’ll hatch and continue their life cycle.

Thoroughly washing those containers ensures you’re removing any surviving eggs and reducing the possibility for a future infestation.

Other methods that can kill mosquitoes in stagnant water include using apple cider vinegar, liquid soap, mineral oils (vegetable oil, cinnamon oil, virgin olive oil, etc.), and mosquito dunks or bits.

The method of application and mechanism of action of these treatments will be discussed further in this article.

How to kill mosquitoes in plant water

Plant pots and flower vases sometimes contain excess water from rain or regular watering. Weekly plant water changes will prevent any further development of mosquito larvae that may be present. If you can, thoroughly wash any vases or plant pot trays; biweekly or monthly cleaning is enough to get rid of any attached eggs.

For adult mosquitoes, use any commercial or homemade insecticides and larvicides. This will kill the adults and stop them starting a new breeding cycle.

You shouldn’t use bleach or chlorine for plant water, pet bowls or kiddie pools, as it can kill the plants or your pets along with the mosquito larvae. 

When selecting the best method to kill mosquitoes in any water body, you need to weigh your options properly so you don’t do more harm than good. For instance, you don’t want to use apple cider vinegar, mineral oil or kerosene in a koi or fish pond because they can kill the fish.

How to prevent mosquitoes in and around your home

There are simple and natural approaches to prevent mosquitoes from invading any part of your home.

Keep the environment tidy

Contaminated or unsanitary water bodies provide food for mosquito larvae. Proper waste disposal and monitoring of all possible sources of standing water can significantly reduce the chances of mosquitoes choosing your home as a breeding ground.

Repair any leaks or cracks

There are certain leaks that could go unnoticed by an unsuspecting eye. It only takes a few drops of water from a leaky air conditioner, sink, or pipe for mosquitoes to start laying their eggs. If you find any leaks, repair them sooner rather than later.

Keep the trash covered

Some trash bins collect rainwater and can be a haven for mosquitoes. If you can keep the lid on and make a habit of draining the lid itself after it rains, that’s one less breeding ground for mosquitoes.

You can also fix a small drain or hole at the bottom of the trash to let out any rainwater water that manages to get in.

Keep any open water bodies moving

Mosquitoes breed in stagnant or still water. So, your ponds, pools, or fountains are only attractive if they’re still for a long time. Amazon has some great devices to keep the water in motion like:

These will also kill any larvae present because the water surface becomes turbulent and affects their ability to siphon air.

Remove excess vegetation

Mow your lawn on a regular basis. Mosquitoes don’t breed in vegetation, but it provides a comfort zone (moisture) for resting and gives them access to organic debris they need to survive.

Use natural repellents

These are categories of natural products that keep mosquitoes away without necessarily killing them. Burning citronella oils or scented candles can emit odors that repel mosquitoes.

All of the following plants are available from Amazon as live plants or seeds and are known to keep mosquitoes and other insects away:

The fastest way to kill mosquitoes is to target the larvae and the easiest way to prevent mosquitoes is to remove all potential breeding grounds. If adult females can’t land in an ideal place to lay their eggs, you won’t have a mosquito problem on your hands.

Chemical and commercial ways to kill mosquitoes in water

Killing mosquito larvae is straightforward, using the right chemicals. Larvicides are insecticides specifically made to kill mosquito larvae. They help to reduce the population of mosquitoes in any area and come in different physical forms such as liquids, granules, tablets and other formulations.

Government approved larvicides in circulation are methoprene granules (link to science direct article) and mosquito dunks, also known as BTI dunks (link to EPA).

Methoprene granules

These are growth inhibiting hormones that prevent the development of mosquito larvae. It is easily distributed into the affected water and can be left long enough to ensure that the larva never proceeds to the next stage in the life cycle. It is highly effective and safe for the environment.

Altosid Pro-G Mosquito Larvicide by Zoecon are an excellent 1.5% methoprene larvicide available on Amazon. These granules are also safe for fish ponds, pets, and other wildlife.

Here’s a simple guide on how to use methoprene granules, in addition to the manufacturer’s instructions:

  1. Know the volume of the water that you’re planning to treat. The instructions for use on these products are always based on size, so it’s important that you have an idea of the size of your water tank, barrel, or fountain.
  2. Use protective clothing like gloves and eye goggles. Despite its safety to the environment, your skin might not be very welcoming to the chemical.
  3. Measure the specified quantity of the granules with respect to the water volume.
  4. Sprinkle the granules on the water surface and leave it to stand.
  5. Remove the protective clothing and wash separately from the general laundry.

BTI dunks and bits

BTI dunks and mosquito bits contain a species of bacteria called Bacillus thuringiensis israelensis.

BTI dunks are small, ring-like structures that slowly dissolve when thrown into water and kill mosquito larvae.

At the larva stage, mosquitoes feed on bacteria present in water. Introducing these bacteria-rich substances is equivalent to poisoning their food. Naturally, they ingest the BTI dunks or bits which in turn causes gut poisoning that eventually kills them.

This control method has no adverse effects on water quality, so it is safe for treatment of pools, pet bowls, plant water, and basically, any affected water holding structure.

It is an effective method that has even been applied through aerial spraying on a large scale.

You can find Mosquito Dunks or Mosquito Bits at an affordable price on Amazon.

Organophosphate insecticides

This is applied on different kinds of water bodies and has a high larvicidal potential. It affects the nervous system of insects at larvae and adult stages.

Some common household products with effective larvicidal properties include:

Cinnamon oil

Cinnamon is a kitchen condiment used in many households almost everyday, and evidence supports the effectiveness of cinnamon oil against mosquito larvae. It has the ability to prevent mosquito development as well as give the water an appealing fragrance once you’re done with the treatment. You only need 1% solution of cinnamon oil to get results.

You can prepare 1% solution of the oil by mixing about a quarter teaspoon with four fluid ounces of water. This solution can be sprayed on the surface of the affected water body, and because of the quantity required might only be suitable for small bodies of standing water like water fountains, fish-free ponds, puddles, kiddie pools and buckets.

Cinnamon oil is also available for purchase on Amazon.

Mineral oil

Mineral oil create a thin layer on any water surface. This prevents air passage into the water which suffocates mosquito larvae and kill them. It is a very effective method that is suitable for plant water, fountains, fish-free ponds, and certain water vessels that wouldn’t require subsequent cleaning after treatment.

Mineral oil is a common household product used for restoring and protecting wood surfaces and can be purchased from Amazon.

Does paraffin kill mosquito larvae?

Medicinal or liquid paraffin oil (Amazon link) is a cheap but effective way of killing mosquitoes in water. Liquid paraffin can be used to kill mosquitoes in water tanks, but it also has it’s disadvantages including some reports of coagulation on the sides of the tank.

The recommended dose of paraffin oil is about a half teaspoon for a 50 gallon water barrel, or roughly 2 gallons of paraffin oil for a 10,000 gallon tank.

Does kerosene kill mosquito larvae?

Kerosene is an excellent remedy to mosquito problems. The larvicidal mechanism is similar to that of soap and mineral oils.

Kerosene reduces the surface tension of the water which affects the ability of the larvae to float. It also prevents the females from depositing their eggs in the water surface.

When the larvae can’t float, they can’t breathe. And like every living organism, without air they die within a short period of time. You can use kerosene for rainwater tanks, and other standing water bodies that are not in direct contact with aquatic animals or plants.

Add about a quarter teaspoon of kerosene to kill mosquitoes in a full 50 gallon water barrel, or 1 gallon of kerosene for a full 10,000 gallon tank. This amount is not harmful to humans, but adding higher doses can make it taste bad and become poisonous. That’s also why it’s important to first check the water level and adjust the amount added as required.

Note: Industrial or commercial kerosenes should NOT be used in water used for drinking (such as rainwater tanks). You also need to be careful that the rainwater tank being treated with kerosene does not have a Polyurethane coating on the inside. Kerosene can react and degrade these coatings, which can end up in your drinking water.

An alternative way to use kerosene is to burn it in a lantern as you would use citronella oil. The fumes from this would only repel adult mosquitoes from a particular area, and not kill the larvae or the adults. It is an effective way to mask the human scent while relaxing or working outside in an area with mosquitoes.

Does algaecide kill mosquito larvae?

An algaecide is any chemical or biological substance that can be used to destroy or prevent the growth of algae. Pool water or water fountains can be treated with a good algaecide (Amazon link) on a weekly basis to manage algal growth and maintain a clear water surface. It also gets rid of slime mold and pathogens.

Mosquito larvae feed and survive on algae as well as some microorganisms. Algaecide does not kill mosquito larvae, but it can reduce the amount of food available for them to eat. Algaecides would only kill mosquito larvae if it’s rich in copper sulphate and/or if algae is the only source of nutrient for the larvae in the water.

Does chlorine kill mosquitoes in water?

Chlorine is a widely known disinfectant for water bodies. It is capable of killing bacteria and preventing algal growth, both of which serve as food to the mosquito larvae. Chlorine granules or liquid chlorine can be used for this purpose.

Chlorine stunts the growth and development of mosquito larvae, and eventually kills them. It also prevents cloudiness of the water body and maintains the future health of the water, especially when applied periodically.

Can soapy water kill mosquitoes?

Mosquitoes survive on water surfaces because of the surface tension which helps the larvae suspend themselves using a special siphon. When you add any kind of liquid soap to water, it changes the surface tension such that mosquitoes aren’t able to stand or float, and they drown.

Unlike other treatments or preventive measures that target the larvae, using soapy water or drops of soap is effective against both the adults and the mosquito larvae.

Shampoos and other foamy products can function the same way as liquid soap. All you need is about one milliliter in a gallon of water, and the larvae will be dead within a day.

Can vinegar kill Mosquitoes?

Any type of vinegar can kill mosquito larvae, including apple cider vinegar. Apple cider vinegar is a common household product widely used for its health benefits. It is also an eco-friendly solution to mosquito larvae in standing water.

What you need to do is make sure that you apply vinegar so that the water is 15% vinegar, and 85% water. For every gallon of water, you’ll need about 110 fl oz of vinegar (or 150 mL vinegar per litre of water).

If you’re not sure of the exact amount of water, try and add at least a fifth of the total water quantity; more is better. With this method, the mosquito larvae will be dead within 18 hours.

Will Epsom salt kill mosquito larvae?

Epsom salt is a naturally occurring mineral also called hydrated magnesium sulfate crystals. It is one of the many unconventional methods that has been used as an insecticide and mosquito control measure.

There is currently no scientific evidence to prove the effectiveness of Epsom salt against mosquitoes. However, some people used it in a mixture of other household products like beer or mouthwash (I think they were just mixing it with anything they could find!), and claimed to have gotten a positive result.

Conclusion

Prevention, they say, is better than cure. To stop mosquitoes from taking hold in your environment, you should have a plan for every body of water around your property. Water is life to mosquitoes, no matter how small. So, as long as there’s rain, mosquitoes are something to worry about. 

When selecting a mosquito treatment method, be sure that it’s a safe option for you, your pets, and other beneficial wildlife that use the water around you.

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