Tadpoles, mosquito larva and alternatives

In the past few years we have had an exponential increase in the number of tree frog tadpoles living/ growing in 3 of our water barrels. Unfortunately a similar increase in mosquitoes as well. We love hearing the mature tree frogs and watching the tadpoles grow.
Tree frog tadpoles do not eat mosquito larva
A number of people have championed the BT dunks. I hesitate to use them. Exclusion techniques for mosquitoes would likewise exclude or hinder the tree frogs and tadpoles.
We are in a small Midwestern town, but have attracted lots of dragonflies and some bats. We are now contemplating purple martin houses, but are unsure if we could even attract them in this suburban setting.
Anyone have any suggestions based on first hand knowledge of either the 100% safety of said dunks on treefrog tadpoles in small bodies of water or of another viable alternative to encourage treefrog breeding but not mosquitoes?
Thank you!

We have kept Japanese rice fish and also white cloud minnows in outside tubs, they will eat mosquito larvae but may be small enough not to go after your tadpoles.

That is brilliant, and just what I was looking for! Thank you!!!

I have to ask, frogs in water barrels? Like are they open top irrigation water barrels?

I wonder if you could encourage frogs towards like a pond structure (if you had the land/time/effort) and then seal up the barrels to kind of separate the two.

I'm just nosey, but would you be willing to post a picture or two of your setup?

There is a fish called mosquito fish. They are very similar to minnows but a little smaller. Just about any petco or similar should stock them.

Good luck on the martins. I have 2 Martin mansions that I spent way to much on. No martins yet it’s been 2-3years. Maybe next year.

Guppies are great at hunting mosquito larvae, and they can survive a lot but don't like it too cold ("if you're cold they're cold" kind of thing).

We pump water from our 325 gal IBC totes into open 50 gal water barrels located just outside the doors of our cattle panel high tunnels. We then use those barrels for hand watering the high tunnels. ( It's my husband's thing)
Although last year they simply became treefrog nurseries, and other than the mosquito issue we're okay with that.
We have lived here over 25 years and 2 years ago was the first time we had tree frogs. We want to encourage them along with everything else!

While we have a small pond, it's occupied by koi and common toads and their tadpoles most of the spring and early summer.

Thank you for clarifying, I'm going to read up on tree frogs now that I have started down the amphibian rabbit hole. Got to love more diversity of animals!

I have now hit a big husband shaped bump in the road. Further investigation turns up that all mentioned fish species are non- native and mosquito fish were called out specifically as invasive. My husband spent a number of years before retiring working to prevent asian carp from getting to Lake Michigan. Therefore anything that has the potential to be an issue down the road, well intentioned or not, is now a no go here.
Now going down rabbit hole looking for a native species fish that doesn't like tadpoles. And pricing Martin houses...😁

While it is not a clear cut solution to where you would eliminate ALL the mosquitos, I wonder if planting plants that have a tendency to repel mosquitos might divert them from trying to populate your water barrels.

I'm thinking lavender, marigold, beebalm?

Maybe do an herb planting of sage, basil and rosemary?

I can agree with that position. Hmm I think that probably going to leave fish out in general as bigger stuff can eat tadpoles.

While it won’t completely solve the problem a cheap solar aerator will help.

Back to the drawing board.

Joe - I agree. Fish, especially native to my Midwest home, are probably not going to work after all.

Tim- you may be on to something, but I'm thinking of a small modification. I already grow most of those herbs and within feet of my rain barrels. Hasn't made any real difference. However I'm wondering if said herbs were harvested and crushed to release their essential oils and put in a small, shallow plastic deli container and floated on the water's surface if it would be enough of a scent deterrent.The herbs could be easily refreshed on a regular basis.

Now we just have to wait 5 months or so for the experiment to continue!

I did the research on BT dunks some years ago with concern for local dragonfly larvae.

BT stands for Bacillus Thuringiensis. It occurs naturally in the soil and has been farmed and used extensively for mosquito control over the last three decades.

It kills the larvae of mosquitoes, blackflies and fungus gnats only. It's about as targeted a biological attack as you can get.

However...

Amphibians are very susceptible to changes in their ecosystem, and recent studies have shown that BT doses may affect their intestinal microbiota and gene expression. Their tadpoles may take slightly more or less time to become frogs. They may become more or less susceptible to parasites.

In short, an application of BT won't kill them (especially if they're not eating mosquito larvae), but it may change them.

However, since BT is a naturally occurring organism, such a change may have occurred without your help in a more natural setting.

Should you choose to use it, I would only use it in the barrels, and I would wait until you see the first hint of mosquitoes for the season (BT effects mosquito larvae, but not pupae or adult mosquitoes - the function being that it causes larvae to stop eating). Since you know the capacity of the barrels, you should be able to restrict the dosage appropriately, and limiting the treatment to the barrels alone should reduce any potential risks to the local population.

You mentioned a solar aerator, which made me think of something.
Solar powered fountains are cheaper, but a fountain leads to lots of evaporation.
This video offers an alternative that might work:
https://youtu.be/ybnnPXLSPNs?si=pRz93kgEQTu11Vo-

It is a venturi system, where the force of the pumped water is used to draw air into the water.

A carefully designed filter could remove the floating larva and leave the frog eggs.

The aerator could be perfectly adequate.  Anything that regularly disturbs the water surface should do it, and of course that will be great for the vertebrates.

What about timing? Are the frog eggs laid and fertilized before the mosquitos come? A window screen cover applied at the right time could do wonders, if the frogs get there first. Maybe remove it about the time the tadpoles get both pairs of legs, in order not to hinder their emergence?

Mosquitoes do not like moving water, the larvae eat algae. Also a key food for tadpoles, so you already have some competition for resources.
Lemon scented plants seem most effective at repelling adult mosquitoes. lemon thyme, lemon sage, lemon grass, but the disclaimer is I don't know what the effects on frogs might be but I suspect minimal.
there are nice little submersible pumps for 10-20 bucks that run on 12 volt dc current if you want to entertain the possibility of a waterfall or fountain.

The aerator mentioned earlier is also one way to keep the water from being stagnant.

There are diy traps that use a black sock and soda bottle half full of water.  I'm a little rusty on the measurements etc, but the idea is to cut a hole in the side of the bottle, cover the whole thing with the sock, and push the sock into the hole so the water level is right about at sock level. mosquitoes lay their eggs, larvae swim around inside the bottle but then can't get out when they turn into adults.

Here's a link that has a version of the bottle trap as well as a couple others.

mosquito traps