Do Mosquito Dunks Harm Bees? Here Are the Facts

by Derrick | Last Updated: October 18, 2021

Mosquito dunks are some of the most useful tools to get rid of larvae in still water. They use a fungus to get rid of the young mosquitoes, preventing them from growing. These helpful dunks are great for yards, farms, and more; But many homeowners are worried about having a negative effect on the local bee population.

Mosquito dunks don’t harm bees because they can’t get sick from BTI (Bacillus thuringiensis subspecies israelensis), the primary active ingredient in the insecticide. In fact, mosquito dunks aren’t harmful to bees, birds, humans, and many other species. They can harm gnats, flies, and other insects.

Throughout this article, we’ll cover why mosquito dunks are safe to use around bees, where you can place them, and why they’re one of the most effective applications for invasive mosquitoes. We’ll also discuss which species can be hurt by mosquito dunks.

Do Mosquito Dunks Hurt Bees?

Using mosquito dunks has been proven to be an effective method of mosquito control, but it can harm thousands of other insects. Since bees are a crucial part of almost all local ecosystems, it’s natural to want to protect them. The good news is mosquito dunks won’t hurt bees, so let’s dive into a list of reasons why below.

  • Bees aren’t harmed by BTI (Bacillus thuringiensis subspecies israelensis) found in mosquito dunks. According to Tree Hugger, mosquito dunks are widely used because they’re harmless to people, bees, and many other local species. You’re safe to use any form of BTI without worrying about hurting nearby hives.
  • Most bees don’t fly low enough to ingest the BTI, even if they were susceptible to the ingredient. Bees typically don’t go lower than the flowers they gather pollen and nectar from. Once they get this source, they travel back to the hive. They search for high water sources to drink, so it’s unlikely they’ll come in contact with a mosquito dunk.
  • Bees lay their eggs at the bottom of a cell in their hive, not on the water with mosquitoes. The primary reason mosquito dunks are so dangerous to mosquitoes is because they lay their larvae in the water. Since bees always stick to their hive for breeding and egg-laying, they’ll never hatch near a mosquito dunk.

As you can see, there are more than enough reasons to use mosquito dunks and other BTI products without harming bees. They’ve been used for decades without mosquitoes developing an immunity. If you want to learn more about proper placement, read on.

Where Can You Safely Put Mosquito Dunks?

Since not all insects are immune to BTI, it’s important to place your mosquito dunks in safe places. Not only that but putting a dunk in a random location will likely render it useless. They have to slowly dissolve, filling the water with bacteria. If the water is flowing, it’ll have a hard time getting the job done.

Here’s a list of places you can safely place mosquito dunks:

  1. Place mosquito dunks in still bodies of water where mosquitoes go to lay their larvae. Mosquitos naturally search for non-moving water because they can keep track of their eggs. Dirty swimming pools, birdbaths, puddles, lakes, and ponds are primary targets for mosquito larvae to grow, so place the BTI nearby.
  2. You can use BTI in other forms, including sprays, to control mosquitoes without using mosquito dunks. According to the EPA (US Environmental Protection Agency), you can use several forms of this bacteria around your home without causing damage to you, your pets, bees, butterflies, and other local, productive insects.
  3. Apply the dunks or spray close to the ground rather than in higher pools of water (on your roof, near other insects, etc.). Mosquitoes search for the lowest pool of water to encourage their larvae to hatch, grow, and fly. Since most other insects steer clear of these areas, they’re perfect places for mosquito dunks to dissolve and do their work.
  4. Mosquito dunks aren’t as effective in moving bodies of water since they dissolve and flow down the stream. While they’ve been used countless times in streams and rivers, these dunks do best when the water isn’t moving. It’s still worth trying if the water is moving and you’re dealing with mosquitoes, but it might take longer to show results.
  5. You can use mosquito dunks in bird baths to keep them safe from Zika and other common mosquito-borne diseases. Birds often get bit by mosquitos, spreading dangerous diseases around the world. If you have a birdbath, it’s a primary target for the local mosquito population to breed and lay their eggs.

The Summit Responsible Solutions Mosquito Dunks provide an eco-friendly solution to your mosquito problems. Place one dunk into a body of water up to 100 square feet and watch as it removes the larvae for up to 30 days. They’re an effective, incredibly simple way to handle a frustrating pest infestation.

Will a Mosquito Dunk Harm Other Insects?

Humans, pets, and most insects are safe from BTI. The bacteria doesn’t cause internal issues, nor will it lead to starvation. However, Insect Cop explains mosquito dunks are potent against over 2,500 insect species, so they’re not all safe. Most of them are considered pests, which means your BTI can be a two-in-one ingredient.

So, what other insects are harmed by mosquito dunks?

Mosquito Dunks Can Hurt Black Flies

Black flies do little harm other than cause minor annoyances. Whether you’re tired of hearing their buzzing sounds or them landing all over the place, you’ll be glad to know BTI products (including mosquito dunks) can have the same harmful effects on black flies as mosquitos. 

Black flies often lay their eggs near moving water, so this might be worth considering when placing your mosquito dunks. However, some flies will choose still water sources if there’s not enough clean moving water available.

Fungus Gnats Can’t Live Near BTI

Fungus gnats are quite frustrating because they wreak havoc on fruit trees, potted plants, new soil, and more. They can ruin the appearance of your plants and cause them not to get enough water. Fortunately, mosquito dunks will get rid of fungus gnats.

Much like black flies and mosquitos, fungus gnats spend most of their lives in search of water for drinking and laying eggs. One mosquito dunk is often enough to wipe out a local population since they’re a fraction of the size of a mosquito.

Whether you’re taking on mosquitos, black flies, fungus gnats, or other small pests, mosquito dunks should be at the top of your list. These safe, effective treatments are used by homeowners and professional pest control teams alike.

Not only are they good for removing these pests, but they’re actually beneficial for bees because they don’t have to compete for water and other natural resources. BTI is one of the limited options for those preserving bee populations.


Now that you know how effective mosquito dunks are against mosquitoes and not bees, you can safely use them around your home. They work best in still bodies of water where mosquitoes lay their larvae. Once you starve the population, you won’t have to deal with nearly as many biting and buzzing. Good luck!