Best Mosquito Dunks – how to use them and how they work

More often than not when combatting mosquitoes, it is always better to attempt to attack the source of the problem than it is to attempt eradicating such a mobile and far-ranging pest. Mosquitoes breed at a staggering rate and a female can lay upwards of 500 eggs per lifetime, ensuring that an endless supply of mosquitoes will continuously thrive in a region.

This site strives to offer the best advice on a wide array of products, yet sometimes, it is also helpful to look to natural science to find out if an alternative to insecticides is truly as powerful as chemicals. Mosquito dunks are one such product that meets all of the criteria to ensure successful pest control.

In this guide, we will explore one of the more elusive, yet highly effective products for mosquito control–the mosquito dunk.

What are the Best Mosquito Dunks?

If you are looking for the best mosquito dunks and larvicide to buy on the market, then we recommend the following which can be purchased from highly reputable company:
best reviews of mosquito dunks

What Are Mosquito Dunks?

A mosquito dunk is a small, round tablet with a centered-out hole in the middle that is meant to float on top of standing water. The tablet is made entirely of a bacterium known as Bacillus thuringiensis (B.T.I.), which is an insect larvicide that kills mosquito larvae that emerge from hatched eggs on top of standing water.

Mosquito control frequently teaches us that multiple efforts and strategies are best when seeking success with this complex pest, therefore, a control strategy that addresses larvae before adulthood can be achieved represents the ultimate method for destroying a problem before it is ever able to evolve into one.

A mosquito dunk works well in swimming pools, bird baths, flower pots, water garden displays, and any large areas that contain standing water. This product is as easy to use as simply dropping the tablets into the water, which produces results that are incredible for such a simple process.

How Do Mosquito Dunks Work?

The mechanism of action of mosquito dunks is decidedly simple, drop the tablets into stagnant or still water, and the product will dissolve to create a bacterium barrier on the surface of the water. The larvicide aims to target mosquito larvae specifically, which is the life stage immediately after the hatching of an egg.

Mosquito larvae spend most of their time in surface water, which is where adult mosquitoes lay their eggs to prevent any possible disruptions in the life cycle below water. B.T.I will coat the surface water to upwards of 100 square feet of surface coverage.

Once the larvae begin to swim into the surface water, bacillus thuringiensis immediately begins to kill the larvae within hours of exposure. Although mosquito dunks can 30 days, the Journal of Herpetology recommends treating standing water every 7 to 14 days to ensure complete and total eradication.

In addition to treating the surface water, the larvicide will also begin to travel throughout the remaining square feet of standing water to cover the entire surface. This is an added benefit since larvae will likely begin to travel away from the larvicide over time.

The larvicide does not immediately kill the larvae on contact, rather, the bacterium is eaten by mosquito larvae, which is then toxic to the larvae digestive tract. The efficiency of this product is highly potent and will eradicate an entirely new population of mosquitoes before the insects even reach adulthood.

You can use mosquito dunks to kill larvae

How Long Do Mosquito Dunks Work For?

Mosquito dunks are essentially a bacterium that is activated once it dissolves within the water. To better understand how B.T.I. works, it is essential to learn how mosquito larvae operate.

Mosquitoes have breeding spots and water is universally associated with them. Mosquitoes love to breed and hibernate in moist environments.

Any matter that is saturated with water, such as mud, water-logged trees and leaves, and even soil in areas that feature consistent rain, can be used as an egg habitat for mosquitoes. The eggs can hatch in only a matter of days and in some cases, immediately.

Mosquitoes will also deposit eggs in safe areas prior to the first freeze after a hot season, ensuring that new batches that have dried out are ready to hatch once humid temperatures resume. The eggs drift on top of the water in a state known as diapause and can be incredibly hard to see with the naked eye. Once hatched, the larval stage begins.

Mosquito larvae are aquatic creatures that feed on algae, bacteria, and other microorganisms in the water. Certain mosquito species will even eat each other.

Larvae spend most of their time hanging upside down at the surface, sucking in oxygen from breathing tubes located in their tails. This is the only time that mosquitoes will feed on other substances other than human and animal blood.

Because mosquitoes are cold-blooded and rely on external heat sources to warm their bodies, development depends on the temperature, the warmer it is, the faster the mosquito larvae will grow, and you can usually see mosquitoes at this stage due to their moving across the water.

This is where the benefit of mosquito dunks come into play. Dunks treat up to 100 square feet of surface, and the most pleasing benefit to this form of mosquito control is that the dunks last up to 30 days and sometimes, even beyond that.

The bacterium begins to break down within hours, meaning that already present mosquito larvae will begin consuming the B.T.I within hours of activity. Some forms of dunks can also even be reusable, such as BTI Mosquito Dunks, which will make the investment even more beneficial.

Since mosquito larvae are typically in this stage for roughly two weeks, one mosquito dunk in 100 square feet of surface water can realistically kill two larvae generations.

Are Mosquito Dunks Safe?

There are very few methods in mosquito control that are 100% safe, yet mosquito dunks may very well be the only product that can truly prove mosquito control wrong. Since dunks are made to address mosquitoes before they reach their dangerous adult state, this is one factor that makes this type of mosquito control safe.

According to the Washington State Department of Health, B.T.I is well-tolerated in most organisms, however, this bacterium is lethal to the digestive tract of mosquito larvae. Mosquito larvae cannot digest this bacterium effectively and since larvae feed on microorganisms across water surfaces, the insects will most certainly eat the B.T.I in droves.

The natural question to ponder would be if the bacterium is truly safe for wildlife that drinks treated water, and the answer is yes. This is why a water garden is frequently treated with mosquito dunks because more complex animals possess the required gastric enzymes to adequately digest B.T.I.

Mosquito larvae are an anomaly in this regard, which also makes mosquito dunks an amazing form of mosquito control since the insects cannot develop a resistance to the bacterium at this life stage. Since a dunk lasts for 30 days, mosquito larvae are the only organisms in the treated water that have to worry about toxicity.

This is also relevant to humans as well. If the treated water is accidentally consumed, such as in swimming pools, the only dangerous substances would likely be the other chemicals or microbes in the water, not the B.T.I.

Therefore, mosquito dunks are generally safe for every type of organism except for insects in the larval stage. Your pets and/or children will be perfectly fine if treated water is accidentally consumed.

Since mosquito dunks can be potentially irritating to the skin, you should always wear gloves when handling the dunks to avoid slight irritations. Possible eye irritations are also possible with dunks, therefore, you should avoid touching your eyes after handling the products.

Can I Use Mosquito Dunks in My Pool?

Of even more concern than areas of standing water being treated outdoors, a swimming pool is the most pertinent concern for people who decide to use this form of mosquito control. Pools are regularly used by homeowners and the safety of the water is crucial.

Mosquito dunks can be used in pools and are just as safe in swimming structures as the products are in natural areas around a home. With this in mind, mosquitoes do not generally prefer to lay eggs in pools that are currently being treated with pool chemicals.

According to the Ecology Center, untreated and unfiltered pools can be overwhelming breeding grounds for mosquitoes, which is where the usage of mosquito dunks can help greatly.

Pools are not generally used year-round, therefore, treating the pool with mosquito dunks which lasts for 30 days at a time is a great way to practice mosquito control in the off-season when your pool is dormant. Furthermore, you can also use dunks during the time of year when your pool is in use.

B.T.I is not harmful to humans, so feel free to add mosquito dunks to your existing pool chemicals, although it is quite possible that the bacterium may not survive as long in conjunction with harsh pool chemicals.

But with frequent usage of chemicals such as chlorine, it is highly unlikely that mosquitoes will choose to lay eggs in an already treated pool. Prioritize treating your pool with mosquito dunks during the months you are not using your pool, regardless of when you use the dunks, there are no overt safety concerns when using this product in your pool.

Do Mosquito Dunks Really Work?

When observing the effectiveness of mosquito dunks in the wider sphere of overall mosquito control, dunks are so highly recommended due to both the high kill rate and the safety of the products. Mosquito dunks are chemical-free and represent a marvel of nature working to reduce pests as destructive and dangerous as mosquitoes.

With this in mind, it is important to remember that mosquito dunks do not kill adult mosquitoes, the product is only effective at killing mosquitoes at one specific life stage. If used correctly, dunks can eliminate vast numbers of mosquito populations.

Always keep the following in mind when using mosquito dunks:

  • Mosquito Dunks can treat up to 100 square feet of surface water. You will have to adequately measure how many square feet of surface water is in the area to be treated and adjust accordingly.
  • A mosquito dunk lasts for 30 days. Since it is impossible to know if eggs have been laid within the last 30 days, you may want to retreat every 14 days just to be sure.
  • Mosquito dunks start working immediately. If you use the dunks and notice increased larvae activity, this is likely a natural occurrence of where the larvae are increasingly consuming the bacterium.
  • If other mosquito control measures can be taken, consider applying those first. Mosquito dunks are meant to treat water collections that cannot be drained, therefore, if you can empty smaller units with standing water, always prioritize this action first.

A mosquito dunk is a powerful tool to use in mosquito control. Just remember, dunks are a control measure, not an active chemical that kills adult mosquitoes upon sight.

This product certainly works when used correctly.

Best Mosquito Dunks - Reviews

The following are two of the best mosquito dunks available to buy. If you have water on or anywhere near your property then we recommend the following products:

BTI Mosquito Dunks

BTI Mosquito Dunks

BTI Mosquito Briquets are amazing for the fact that this product will actually branch out and kill varieties of psychodid flies in addition to mosquito larvae. The method of action involves simply placing the briquet in any area of standing water, including bird baths, flower pots, small lakes, and any reservoir containing standing water.

This product will cover up to 100 square feet of surface water and lasts for 30 days. An added benefit of this product is a complete safety guarantee for pets, fish, and any other animals that also comes into contact with the treated water.

Any insect that deposits eggs into the water can be affected by BTI Mosquito Dunks, which is also beneficial for large fly infestations. This product is highly recommended for the product's ability to be reused continuously after multiple treatments.



Mosquito Dunks by Summit

Summit Mosquito Dunks

The brand that started it all is still the most widely purchased brand of mosquito dunks on the market. This product utilizes the most universal methodologies frequently used with mosquito dunks.

Mosquito control measures are guaranteed with this product due to the larvicide working to destroy mosquito larvae within hours. All of the typical measures observed in mosquito dunks are present in this product: 100 square feet of coverage, 30 days of effectiveness, safety to other animals, including pets, fish, and surrounding wildlife, and usage is all structures with standing water, including swimming pools.

If you have decided to invest in mosquito dunks, this is the version that defines the product.



Will Mosquito Dunks Hurt Plants?

Soil and moisture go hand-in-hand when it comes to mosquito breeding grounds. This aspect of mosquito activity is usually a bit of a surprise to many people who normally assume that mosquitoes only breed in water.

Thankfully, mosquito dunks are just as effective in soil and around plants in addition to being completely safe. There is no need to be concerned that the plants or crops will become contaminated by the dunks since a mosquito dunk is completely chemical-free.

Water naturally soaks into the soil, which is when mosquitoes deposit their eggs, therefore it is usually best to place dunks around plants during a watering session. Your plants will be 100% safe and the bacterium will only kill mosquito larvae.

Will Mosquito Dunks Kill Any Other Mosquito Life Stage?

The larval stage is when future mosquitoes are the most active in the water. This is also when the mosquito has a sensitive digestive tract as the adaptability to blood and other substances have not fully evolved yet.

Mosquito dunks are not very effective to any other stage apart from the larval stage due to the larvae needing to consistently feed on bacteria on the surface of the water to survive. This is why it may take a few different treatments with mosquito dunks to effectively kill off a new generation.

Dunks are completely useless when it comes to adult mosquitoes since adults will usually only congregate around water to lay eggs or to look for possible areas to deposit their eggs. If you are combatting a large swarm of adults, other measures like foggers are the best method to use against this life stage.

Will Mosquito Dunks Kill Bees?

Mosquito dunks are meant to be used to kill any water-bound larval stage of an insect species. Since bees do not see any form of their life stage within the water, the bacterium in mosquito dunks is harmless to bees.

What is the Difference Between Mosquito Dunks and Mosquito Bits?

Both dunks and bits are essentially the same things, but mosquito bits are designed to work a lot faster than dunks, which take time to dissolve and destroy the larval stage over longer periods of time. If you want to address the problem quickly, bits are probably a better option.

Dunks are usually more preferred since the process can take time to treat larger areas of water in contrast to the fast-dissolving methodology of mosquito bits.

Can I Use Dunks for Fungus Gnats?

Dunks actually work very well in eliminating fungus gnats. This insect deposits its eggs into moist soil, which makes it a prime target for dunks when the fungus gnats are in their larval stage.

To use dunks for this purpose, simply separate the dunks into smaller pieces and deposit the dunks into the soil. Water the soil to activate the dunks and repeat this process a few days apart.

The product will work on fungus gnat larvae the same exact way that it does on the mosquito larval stage.

Final Thoughts

Mosquito dunks represent one of the safest and most effective ways to wipe-out mosquito larvae before they can become adults. Utilizing the powerful bacterium B.T.I, mosquito dunks dissolve on the surface and are consumed by larvae.

The bacterium destroys the digestive tract of the larvae and can continue to kill an entire colony for as long as 30 days. This product can be used in virtually any structure with stagnant water, either natural or man-made.

100% safe to pets and humans, you can take comfort in the killing power of mosquito dunks without worrying about harmful chemicals. Most packs contain 2, 6, and 20 quantities, which also makes investing in dunks both cost-effective and efficient.

There are many products on the market to combat mosquito control, therefore, investing in a product that seeks to remedy the problem before it gets out of hand is what makes mosquito dunks such an amazing control tool.


  • Earl, Julia. (2014). Ecological Effects and Human Use of Commercial Mosquito Insecticides in Aquatic Communities.
  • Armbruster, Peter A. (2016). Photoperiodic Diapause and the Establishment of Aedes albopictus (Diptera: Culicidae) in North America. 
  • Mosquito Larvicide–Bti. (2020). Washington State Department of Health. 
  • Keeping Mosquitoes Away from You and Your Yard. (2020). The Ecology Center. 

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