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InsectCop Reviews: How Effective (and Safe) are Mosquito Dunks?

Home » How To Get Rid Of Mosquitoes » Mosquito Repellent » InsectCop Reviews: How Effective (and Safe) are Mosquito Dunks?


Mosquito Dunks are one of the most efficient, long-lasting and easy-to-use solutions when it comes to getting rid of mosquito larvae.



  • Works only when placed in standing water
  • Doesn't work on adult mosquitoes

We review a lot of products and product groups on this site, and when we do, we always try to give you the most extensive information possible. We research all scientific and official sources and sift through hundreds of reviews and articles to deliver you the best possible review of the product. This time, however, we went a step further.

We actually purchased the Mosquito Dunks and rigorously tested them for months, to make sure that we are giving you a truly independent, bias-free, and comprehensive review of them. Because, although there is a lot of information on Mosquito Dunks available online, in this review we are doubling down on it and answering every conceivable question about Mosquito Dunks that you might have in hopes of satisfying all of your review needs.

So without further ado, here is our review of the Summit Chemical Mosquito Dunks.

Mosquito dunk basics

Mosquito Dunks, which is a registered trademark of Summit Chemical Co., are made almost exclusively out of a naturally occurring soil bacteria called Bacillus thuringiensis, more specifically its strain israelensis (aka B.t.i.).

Each Dunk is about 2 inches in diameter, the size of a small cookie, and has a narrow hole in the middle to make it easier for you to keep them in place (using a piece of string, a piece of wood or other similar methods) and to prevent them from being flushed out of the area that they are treating.

As Zach Cohen, the Vice President at Summit Chemical Company told us, it all started in the 1980s: “B.t.i. was discovered in the Negev Desert in Israel in 1976 by Joel Margalit, a Professor at the Ben-Gurion University. Summit had a relationship with Dr. Margalit and in the early 1980s began working on a professional formulation using this novel bacteria.” Which resulted in the creation of the Mosquito Dunk predecessor Bactimos Briquets (now the Summit B.t.i. Briquets).

They were then sold to different mosquito control organizations, who distributed them to the general public. However, the product became so popular and Summit received so many questions on where could people purchase these mosquito larvae-fighting briquets that they decided to create their retail brand. So the Mosquito Dunks brand was born, and “for the last 30 years the product has become the staple for biological, environmentally conscious mosquito control.”

In terms of their appearance and texture, Mosquito Dunks are solid, dry, and rough, without being crumbly or brittle. And since they are made out of B.t.i., granular cork bark, and a plaster compound they are also pretty light in weight, which allows them to effortlessly float on the water’s surface, where they can slowly dissolve and release the B.t.i. in the most efficient way possible.

They also have a very light scent that remains unnoticeable in the water or when you are holding or storing the dunks.

Since Mosquito Dunks are made out of a naturally-occurring soil bacteria they, indeed, are eco-friendly and can be used for organic gardening as they are approved by the United States Environmental Protection Agency (U.S. EPA). To quote Zach Cohen: “This is a product that was “green” before eco-consciousness was even a common concept.”

And because Summit is a US-based family-operated company, they produce their products exclusively in the United States of America, in their Baltimore facility. So Mosquito Dunks can also be labeled local. Yet, that doesn’t stop the manufacturer from providing the Dunks to people outside the US, seeing as the product doesn’t contain any harsh chemicals or substances that might be banned in some countries.


If you plan on purchasing your Mosquito Dunks online, you might wonder if they can arrive damaged. And from our own experience, the answer is yes.

The plastic packaging of the Dunks that we received was a bit dented upon arrival but the Dunks inside were intact. More importantly, however, even if they were physically damaged and broken into pieces, they would have still been usable and effective at treating the water containers they are put into since it’s even recommended to break up the Dunks if you want to treat an area that is smaller than the recommended 100 square feet of surface water. So, you shouldn’t hesitate to purchase Mosquito Dunks online if their delivery is what worries you.

As for the packaging itself, the Mosquito Dunks came in standard, commercial plastic packaging, so, while the Dunks themselves are eco-friendly, the packaging is less so.

However, Summit has made strides in making their packaging more eco-conscious. The plastic part of the packaging is chlorine-free, while the back part of it is paper and therefore can be easily recycled. And the sturdy nature of the packaging also means that the Dunks can safely travel to your home and that you won’t be paying extra just for the package of the product.

When it comes to the volume of the Dunks, you generally have a choice between 3 different package sizes – 2, 6, and 20 Dunks.

If you just want to test Mosquito Dunks for yourself, buying a small package of 2 Dunks is advisable. However, since Mosquito Dunks need to be replaced every month, buying a pack of 20 Dunks is the best and most cost-efficient long-term option.


How do Mosquito Dunks fair price-wise compared to other similar insecticide options?

As far as traditional insecticides are concerned, Mosquito Dunks are incalculably more efficient at killing mosquito larvae. A single Dunk dropped in a water container infested with mosquito larvae can kill thousands of future mosquitoes before they’ve even had the chance to take flight. So much so that simple mosquito sprays and repellents might seem almost pointless compared to the level of effectiveness of Mosquito Dunks.

And the convenience of the Dunks and their longer-lasting effect also make them ideal for use over other similar products.

Mosquito Dunks can be more easily anchored via a string, they last longer, need to be replaced less frequently, and they are more practical to use in larger, open water basins since one single dunk can treat up to 100 square feet of surface water which is about the size of a standard-sized single garage.

How do Mosquito Dunks work?

Mosquito Dunks work by gradually releasing their natural larvicide in the water they’re in. The mosquito larvae then simply feed on the B.t.i. larvicide and die from it in a matter of hours.

There have been plenty of scientific and laboratory experiments and evaluations on the effectiveness of Bacillus thuringiensis subspecies israelensis on insects such as Aedes aegypti aka the yellow fever mosquito and Aedes albopictus aka the Asian tiger mosquito. And it’s undeniably clear that Mosquito Dunks work perfectly against all 2,500 different species of mosquito larvae, as well as on insects like fungus gnats and black flies.

However, there is zero evidence that it works against other creatures, including other insects and bugs. So if you’re worried that you might hurt your local bee, dragonfly, ladybug or other beneficial insect population, then there is no reason to be concerned about that.

To take a deeper look into the chemical facts about B.t.i.’s effectiveness, we’d suggest this extensive study on the NCBI.

While mosquito larvae that consume B.t.i. die pretty quickly, in a matter of hours, you can expect to start noticing a diffidence in approximately 2 days and see the full effects of the larvicide in about a week.

Since it kills larvae only and not adult mosquitoes, you’ll still have to deal with the already existing adult insect population or just wait for them to die off. Yet, once this is done there should be no further mosquito generation and any adult mosquito that comes from outside of your immediate environment and tries to populate the waters you’re treating with the Dunks, is bound to fail.

And since adult mosquitoes don’t realize what’s happening to their offspring, they will keep trying to repopulate in the larvicide water and, therefore will effectively doom their own offspring to death.

With each Dunk lasting 30 days and treating 100 square feet of surface water, using Mosquito Dunks will let you cheaply and easily exterminate countless future adult mosquitoes before they even developed their wings.

How to use mosquito dunks to get the best results

Mosquito Dunks are very easy to use as all you need to do is place the correct amount of the Dunks to the appropriate amount of water – one Dunk per 100 square feet of surface water.

The depth of the water container is irrelevant because, as Cohen explained: “In order for the mosquito larvae to consume the active ingredient, it must be released at the water’s surface where larvae generally feed.”

So if you have a water container that has a surface area of about 25 to 100 square feet, float a single Dunk in the container and you should be mosquito larvae-free for a whole 30 days.

If you have a water body of a larger surface area, a large pond, for example, use two or more Dunks.

While if you have a smaller container that collects water and that you want to treat, then break up the Dunk and use only as much of the Dunk as you need. One half of the Mosquito Dunk will treat about 5 to 25 square feet of surface water and a fourth – 1 to 5 square feet of surface.

Just remember that there is no point in using more than one Dunk in the recommended water surface area since it will do nothing but waste the product. The exception, however, is if the water is highly-contaminated, then an increased dose of Mosquito Dunks might be of use.

Where to use Mosquito Dunks?

You can use the Mosquito Dunks in anything that contains water and that can’t be drained or prevented from accumulating water – rainwater barrels, ponds, tree holes, flower pots, rain gutters, swimming pools, animal feeding troughs, septic tanks, water puddles, pet bowls, you name it.

But if you already have chlorine in your swimming pool you won’t need a Mosquito Dunk since the chlorine prevents mosquito larvae from developing anyway. And pool filters and aeration systems also keep mosquitoes away since they circulate the water and keep the water from going stagnant. Instead, you can consider a mosquito fogger machine if you are still worried about mosquitoes.

As long as there is standing water, no matter if the container is outdoors or inside your home, the Dunks will do their job.

They are less recommended, however, for flowing water (rivers, canals, fountains with strong water circulation, and so on), since mosquitoes tend to ignore such water sources and since the Mosquito Dunks just wouldn’t be efficient in water that is constantly moving.

You can also place Mosquito Dunks in dry places such as your garden soil if you know there are heavy rains coming and the soil tends to retain moisture and form puddles (one Dunk to about every ten square meters of dry surface). This will make sure that mosquitoes don’t catch you by surprise by breeding in unexpected places like puddles for example.

When to use Mosquito Dunks?

In terms of when Mosquito Dunks should be used, the general rule is the sooner the better.

Since they kill mosquito larvae its best to target the first annual breeding cycle of mosquitoes by applying the Dunks in early spring (March, April, or even February for some parts of the Northern hemisphere). And continue to consistently use the Dunks all throughout the mosquito season.

So although the Dunks don’t have to be used in the seasons when mosquitoes aren’t active (for example in the winter) you do need to make sure that you are consistent with your Mosquito Dunk usage to truly make sure that no new mosquitoes are breeding in your area.

And if you forget to use the Dunks one month or even for just a few days, don’t fret, place them in the water as soon as you remember and they should start killing mosquito larvae again within hours.

It doesn’t matter at which time of day you use the Dunks, just whether you are using them regularly and whether you are employing additional mosquito control methods to combat the adult mosquitoes that live in your immediate area.

Other points to consider

There are also some steps you might want to take to preserve the Dunk’s well-being so that they can do their job.

  • Make sure that the Dunks don’t get washed out of the water by rainwater or wind, or caught in the weeds of your pond by anchoring them in the middle of the water using a stake, string, or other similar methods.
  • Summit states that UV rays shouldn’t affect the performance of Mosquito Dunks, so the Dunks will be effective even if kept in direct sunlight for extended periods of time.
  • Also make sure that your pets, fish or other animals don’t eat them. All mammals, birds, and amphibians will be one hundred percent fine if they consume the Mosquito Dunks, but this will simply prevent the Dunks from doing their job. Therefore make sure to keep the Dunks in a protective stocking that allows water to pass through if animals frequent the place that you are treating with the Mosquito Dunks or especially if you have fish or turtles as they love to consume them.
  • Additionally, make sure to keep in communication with your neighbors, tell them about Mosquito Dunks and ask them to use the Dunks as well. This will make sure that not only the area that you actually own is free from mosquito larvae and therefore from mosquitoes. But that mosquitoes aren’t breeding nearby and then flying to your backyard and continuing to bother you since mosquitoes usually hang out in one to three-mile radius.
  • And finally make sure you need to use as few Dunks as possible, Meaning, remove all the standing water from your property that you can. There is no point in dipping Dunks in water containers every month if you can simply get rid of the water itself. And with things such as flower pot containers or dog bowls, for example, remember to change their water at least twice a week to prevent the mosquito larvae from maturing in the water.

How safe are mosquito dunks?

As Mosquito Dunks are generally safe for humans and other animals, there are very few safety guidance tips you’ll need to follow when using this product.


You can freely use Dunks in and near soil you use for growing fruits and vegetables as it will not affect their taste or healthiness in any way.

You can also water your plants with water that has been treated with Mosquito Dunks, no matter if it is rainwater, water from a well or any other source because the Dunks won’t do any damage to the plants or to you if you consume the plants that have soaked up the Dunk water.

And Mosquito Dunks can even be placed in plant pots that retain water because they won’t do any harm to the plants growing in the pots nor to the soil in which the plants are growing.


When it comes to animals and other living organisms, Summit Mosquito Dunks are, in fact, safe for all organisms. This includes all animals from pets (cats, dogs, etc.) and livestock (cattle, horses, sheep, etc.) to wildlife (deer, foxes, rabbits, etc.). All birds from poultry and other domestic ones (chickens, turkeys, geese, etc.) to wild birds. All aquatic life no matter if these aquatic organisms are living in aquariums, ponds, lakes, terrariums, or other water reservoirs (tadpoles, turtles, fish, reptiles, etc.). As well as all insects and bugs except mosquitoes, black flies and fungus gnats, including pollinators like bees and other beneficial insects.

So nothing bad will happen if Dunks will be used in habitats of any of the aforementioned entities. Or even if Dunk-treated water seeps in the nearby lake, pond, or any other environment inhabited or frequented by animals, birds and other organisms.


And Dunks are even completely safe to humans.

If you or your child accidentally consumes a Mosquito Dunk or drinks water that had Dunks in them nothing bad will happen. This includes rainwater and groundwater that has been dosed with one or more Dunks.

However, you should avoid putting Mosquito Dunks in treated drinking water. Although B.t.i., the main ingredient of Mosquito Dunks, is safe for us, you shouldn’t drink it in large amounts, because it means that you will be constantly consuming large doses of protein and calcium which can be harmful to some people.

Besides, if you put the Dunks in your drinking water you would essentially be wasting them since you would just consume the water as well as the B.t.i. without allowing it to do its job of killing mosquito larvae that are in the water.

Mosquito Dunks are safe for all humans and animals, as well as plants and other living organisms.

They also won’t damage any mechanical equipment that you might have in the water that you want to treat with the Dunks.

Since they are quite brittle and dissolves over time Dunks won’t clog your water filter, fountain pump, or damage other things that you might have in the water like pond thermometer, light fixtures, or statues.

And you can even wash your car with water that has a Dunk floating in it because the paint of your car will be totally safe and damage-free. Just don’t go using the Dunks as water filters, because although they might look like a water filter, they do not serve this purpose.

Handling, storage & disposal

Standard Mosquito Dunks have a 2-year (24-month) shelf life which is typically plenty of time to use them up since the largest packs have 20 Dunks in them and each Dunk lasts just 30 days.

Handling the Dunks

Although you do not need to wear gloves, safety goggles, a respirator, or any other safety gear when handling Mosquito Dunks you should avoid getting the Dunk particles in your eyes or your skin.

Yes, Dunks are perfectly safe for humans, however, the tiny particles of the dunks, dry or wet, can still irritate your skin and eyes, especially if you are sensitive to different irritants. So if you don’t want to experience any physical irritation, handle the Dunks with care and wash your hands right after.

First aid

What to do if a piece of the Dunk happens to get into your eye?

Thoroughly rinse the eye with running water for about 15 minutes and you should be good to go. However, if the irritation persists you should contact your doctor.

While if you accidentally swallow a piece of Dunk or water that was treated with a Mosquito Dunk, nothing needs to be done. It won’t do you any harm. Yet, there might be a slight irritation for some people, and if that happens to you, again call your doctor for advice.

Storage and disposal

When stored, Mosquito Dunks should be kept in a dry, cool, and well-ventilated area, away from direct sunlight or heat as they can cause the Dunks to deteriorate quickly.

Aside from that, there really aren’t any more specifics about storing Summit Mosquito Dunks. Just make sure your pets or kids don’t find them as they can eat or ruin them pretty quickly too – the Dunks will be harmless to the kids or pets, but they’ll just go to waste if they are chewed up by your dog or ruined by your little one.

And as far as disposal is concerned, Mosquito Dunks are a natural and eco-friendly product so you can dispose of them however you like. The packaging of the Dunks, however, isn’t. It’s made out of non-biodegradable plastic, so be mindful when disposing of it.

Tips for controlling adult mosquitoes

Make sure you use additional mosquito control methods together with the Dunks as they won’t interfere with the Dunk efficiency, rather these methods will help you get rid of all the mosquitoes, not just their larvae.

For example, you should remove as much of the standing water on your property as possible so that you don’t have to use the Dunks all over your backyard.

You can also use window and door screens to keep the mosquitoes out of your home. EPA-registered insect repellents will help you deal with adult mosquitoes and keep them from biting you while you’re outdoors. And the usage of various yard treatments is also beneficial since it will ensure that your outdoor space becomes a mosquito-free zone.

And remember, as long as the Dunks are dipped in standing water, they will do their job of killing mosquito larvae, no matter how you combat the adult mosquitoes above the water. So employing some additional mosquito control methods on top of using mosquito dunks on your property will only help you get rid of all mosquitoes quicker.


Using Mosquito Dunks is one of the best ways how to deal with your mosquito larvae problem because they will kill the larvae in any standing water in a matter of hours and will keep the water larvae-free for up to 30 days. So why not kickstart your mosquito larvae treatment with a solution that even professionals recommend?


Mosquito Dunks containing Bacillus thuringiensis subspecies israelensis are a safe and natural way to kill mosquito larvae before they have a chance to flourish into adult mosquitoes. In words of Summit’s Vice President Zach Cohen, Mosquito Dunks were built to be a non-toxic, green and eco-friendly product “through the use of natural ingredients safe for everything except the targeted true flies”.

You can use them in any container of standing water with little to no concern of your or your kids’, pets’, or your own safety, as Mosquito Dunks are harmful only to mosquito larvae, fungus gnats, and black flies. And they are both effective and efficient, while also working great in conjunction with other anti-mosquito products and methods. So why not try them out and see your mosquito population diminish before your very eyes?

Frequently asked questions

Mosquito Dunks are small, donut-shaped, floatable larvicide product that dissolves in water and kills mosquito larvae.

Mosquito Dunks release a bacteria (Bacillus thuringiensis israelensis aka B.t.i.) in the water. And once the mosquito larvae consume this bacteria, it enters the stomach cells of the mosquito larvae, where it paralyzes their gut and forces the larvae to starve to death.

They are made out of a natural bacterium called Bacillus thuringiensis subspecies israelensis. (B.t.i.). It’s a natural bacteria found in soil. And while it’s lethal for mosquito larvae, it’s safe for other living things.

A standard Mosquito Dunk will last about 30 days in approximately 100 square feet of surface water.

To properly use a Mosquito Dunk just drop an appropriate amount of the Dunk in the water and let it go to work. If need be, you can use the hole in the middle of the Dunk to keep it in place.

After going through a lot of scientific data, as well as conducting our own tests, we can categorically state that, yes – Mosquito Dunks do work and are efficient at killing mosquito larvae.

For an immediate, short-term effect use Mosquito Bits. However, for a slightly slower but a more prolonged effect use Mosquito Dunks.

You can purchase Mosquito Dunks both in various stores or order them online from such retailers as Amazon, Home Depot, and others.

Sprinkle pieces of a broken up Mosquito Dunk on the infected soil and pour water on top of them. Repeat the process in about a week.

Yes, Mosquito Dunks and the water treated with them are 100% safe for both humans and other living creatures including pets, fish, etc.

Yes, Mosquito Dunks are just as safe for children as they are for adults.

Yes, even when consumed directly, Mosquito Dunks will be nothing more than a dose of protein and calcium for your pet.

Yes, dogs, cats, as well as other pets and mammals won’t be in any way affected by Mosquito Dunks, even if they happen to consume them directly.

Yes, Mosquito Dunks are totally safe for birds and therefore can be used in bird baths.

Yes, Mosquito Dunks are harmless to birds.

Yes, Mosquito Dunks are completely harmless for fish even when consumed directly.

No, Mosquito Dunks are safe for tadpoles, as well as other amphibians.


Wayne Cezair

Actually Mosquito Dunks will kill larvae that already exist. Although the sustained release form of Bt-i lasts for a month, it starts working the moment it hits water or vice versa.
If you break up or crumble a Dunk it is exactly like Mosquito bits in its action; that is it releases the Bt-i immediately and lasts for a shorter time than the whole Dunk.
If you have a serious infestation of larvae, simply crumble up the dunk and apply and then add a floating whole dunk for extended protection.


    Thank you for the useful tip!


    Thank you for that information. You just saved me some money.

Maria G. Buckley

How can I use it in my flower plants? I noticed today that we have a lot of small mosquitos in my pots when I was watering my plants.


    You can’t use mosquito dunks in your flower post. But there are other things that you can do and products that you can use to stop mosquitoes from living in your pots.
    Try not to overwater your plants, because mosquitoes will take any opportunity they can to breed in standing water, even if it is on top of your plants’ soil. Also, use well-draining soil and pots with drainage holes on the bottom of them so the water doesn’t collect atop the soil. And dump the drained water that collects in the planter saucer regularly, because if you leave it there it might invite more mosquitoes.
    But if you have plants that need to have moist soil at all times and have to be watered all the time then apply Bacillus thuringiensis israelensis aka Bti to the top of the soil. Most efficient forms of it for plant soil will be Bti concentrate or granules.


    This is a late reply, but those ‘small mosquitos’ in your potted plants might actually be fungus gnats. They won’t bite you, but are really annoying to you, and their larva will damage the root hairs of your plants. If they are fungus gnats, you CAN use the mosquito dunks to help control them (Bti will kill the gnat larva). I put half a dunk in my watering can, and leave it full of water and use that whenever watering the plants with the gnats. It may take 3 weeks of treatment with the Bti-water (to get all the gnats at the various stages of their life cycle), but it is effective. I also sprinkle ground-up dunk bits on the surface of the soil for additional effect.

Maria G. Buckley

What is the best way to control the mosquitos on my grass? The soil is wet because we irrigate it. What is recommended to use in the grass?


    While when it comes to mosquito control for your lawn check out our Best lawn insect killers article, because we have listed several products there that will make sure that there are no more mosquitoes in your grass!


I collect rain water in barrels, and I use it to water my tomato, and cucumber plants. If I use the mosquito dunks in my rain barrels, is the water safe to use to water my plants and eat the food from them?


    Since mosquito dunks contain Bacillus thuringiensis israelensis (BTI), which is a natural, organic and environmentally safe insecticide and is no harm to any living creature (including aquatic life, birds, pets and, yes, also humans) except mosquitoes, you can use the BTI dunks in your rainwater barrels. Just make sure you use the right amount for the size of your barrels. An alternative to using dunks is to dump the water in them once or twice a week since a week is the minimum amount of time that it takes for mosquito larvae to form into an adult mosquito. But that might not be an option for everyone.

Mary Ann Anderson

Thank you. I live in FL and we have a lot of rain. There is always standing water some where and I have a rain barrel. I have been using the dunks since last year. I don’t have large containers just small ones. ALL of the containers are smaller than a bird bath. I break them up and put them everywhere. But I will start noting the calendar date to be sure I am covered ! MA

LJ Long

I get occasional pooling on my lawn after large rainfall. It stays for two weeks. Will the dunks kill my lawn?


    As long as you use the dunks as you should your lawn will be safe. One suggestion though, I would suggest you use mosquito bits rather than dunks on your lawn because the bits will simply be easier to spread throughout your lawn.


How many dunks for a large pond? (2000 s/f)


    If the surface area of your pond is indeed about 2000 square feet then you will have to use a lot of dunks (about 20), since one dunk can treat up to 100 square feet of surface water. It might be more cost efficient for you to look into a liquid larvacide or to just buy dunks or mosquito bits in bulk.

Jeff C

Great site – thanks.
You mentioned that more Dunks may be necessary for “highly contaminated” water. Do you mean algae and the like?
Also, will the Dunks still work if a large portion of the water surface has algae and other “gunk” floating on it?


    By highly contaminated I meant that there is an abnormally high amount of mosquito larvae in the water. As for algae and other “gunk”, it’s hard to say how that will impact the efficiency of the mosquito dunks. However, I’d imagine the dunks would still work even in water where a large portion of the surface is covered in algae. The dunks create an oily film a top of the water that prevents the mosquito larvae from developing into adults, so, as long as the water is stagnant and the film is there, the dunks should help you control the mosquito larvae.

Rene Black

Are they safe for ponds? In some Q/A is says yes, however, I also read to not use in ponds. Which is it?

    Kristiana Kripena

    Mosquito Dunks are completely safe to use in ponds since they contain only B.t.i. which is harmless to humans, all animals, birds, aquatic organisms and even beneficial insects. The only insects dunks have an effect on are mosquitoes, fungus gnats, and black flies.


Thanks for the write up

You answered all my questions

Thanks again


My intermittent pond, a Grady pond, in south Alabama is sometimes about a third of an acre. You suggested a liquid larvacide on May 9th. Anything in particular? Would it also be safe for a pasture? Guess I should compare that to buying the bits in bulk.


    My suggestion would be trying out liquid larvicide by Altosid, since it should be safe to use on pastures as well.


I had read that dunks will kill caterpillars. Is this true?


    Mosquito Dunks contain B.t.i. aka bacillus thuringiensis israelensis which is completely natural and won’t have any effect on caterpillars or adult butterflies.


Hi, my pond has a fountain and water aerators in each corner. Will the dunks still work?


    Mosquito dunks are labeled for standing water so the dunks won’t work well in a pond that has a fountain. However, generally mosquitoes don’t like to breed in moving water, so, if the fountain is on all the time you might not even need mosquito dunks.


    Thank you for your reply.


Do the dunks off-gas or create any hazardous byproducts? I’m thinking of using them in an underground vault that has stagnant water in the bottom, but there is very poor ventilation, and I want to be sure the air will still be safe to breathe.


    Mosquito dunks are generally harmless to pets and people, so using them in such an environment should be completely safe.


Will the dunks still work if I place them in buckets that I fill with water, rather than already pooled water?

    Kristiana Kripena

    Sure. But the whole point of the dunks is to place them in water that already has mosquito larvae in it to kill it, therefore if you plan on artificially creating mosquito larvae breeding spots in those buckets you’re just making more places for mosquitoes to breed in and they will still continue to also breed in the pooled water.

J. Johnson

Deer (or horses) must be eating the Dunks I put in my trough. So I put them in a very fine mesh bag. Do the cork particles need to get out of the bag to distribute the ingredients or will the b.t.i. pass through?
Also, would anchoring them to the bottom still make them effective?
BTW, these REALLY work well.


    I don’t think that would affect the efficiency of your dunks, though, I’m not 100% sure, as I can’t seem to find much info. I think it’s definitely worth a shot. It would also be great if you later on updated us on how it went. We’d like to hear from you!


First question. My pond is covered in pond weed – a think blanket of small green leaves. Will this prevent the efficient spread of the b.t.i. on the water surface?

Second question. Will killing mosquito larvae remove an important food source for young, developing tadpoles and frogs?


    Weeds might affect how the dunks work. Dunks should be staying on the surface of the water where the larvae are feeding. Therefore, if the weeds prevent the bunks from staying there, it might become a problem.
    As for your second question, from what I’ve heard, the bunks shouldn’t hurt the populations.


I thik there is probably standing water under my porch. the porch itself is only about 10 inches above ground so I can’t get under it to see if there is water. There are mosquitos! If I can wedge a Dunk under the porch, will this help keep the mosquito population down even if there is no standing water? Also, if I put a bucket of water just beyond my back patio with some grass clippings will it direct the mosquitos away and solve a bad mosquito problem?


    The dunks need to be on the surface of the water itself. They won’t repel mosquitoes that are somewhere else around. For that, you should look up some other methods of dealing with the problem. As for the bucket, if anything, it would just give them extra breeding grounds, not help.

Hewitt Rose

I have a small overflow pond that fills with water after a rainstorm then drains in a few days. Does one mosquito dunk last for 30 days or do I need to add a dunk every time the pond fills?


    Alternate wetting and drying of the dunks will not reduce the effectiveness.


I am in zone 5 in SW Pennsylvania. When should I stop using Dunks in my pond?


    We suggest using them until September or October.


I followed the package directions for mosquito dunks, watered my plants and about a week later I had no fungus gnats but I also lost most of my plants! The leaves look like they had been scorched! I’ve had these plants for years! One was my Dad’s plant that was over 40 years old! Gone!! Do NOT use these dunks on your house plants! My heart is broken

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