Depending on the container size Mosquitofish are excellent mosquito control. The city may bring some to you for free is you ask.

Mosquito Dunks work too but you have to keep replacing them every few months.

You'd be working at cross purposes however since the mosquitoes would help attract tree frogs I should think.

I have some buckets and small containers that are always full of water. They attract mosquitoes, and for a while I thought they were also full of tadpoles. But the tadpoles turned out to be mosquito pupa, alas. Plenty of them, but no tree frogs yet.

I thought of mosquito fish, but would they eat the tadpoles if I had some?

I could go down to the local creek and find some tree frog eggs, if I knew what to look for. My current buckets and containers with water probably have some algae growing and might be a good place to put the eggs. Is this the wrong time of year to look for eggs?

Mosquitofish will eat small tadpoles.

Check the laws on gathering eggs, could be protected.

A high sided water container will quickly be colonised by any resident tree frogs which will go dip daily and lay eggs in it when the mood takes them.

Azolla, salvinia are floating plants which when they cover the surface of the water, will be an effective obstacle to mosquito laying eggs, but no obstacle to tree frogs laying eggs

Being a permanent body of water, its only a matter of time before small aquatic insects colonise and tend to suppress mosquito naturally

I have 300 gallon stocktanks and the tree frogs love them. The tanks are above ground. I'm thinking 100 gallon is probably the smallest you would want. I do have a couple inground 300 gallon tanks too, but the tree frogs like the above-ground ones. On some summer nights, its almost deafening around here. I love it!
And of course, they like lots of trees and bushes too, although I have found them on the house at times.

Even before I had my pond, I had hundreds of tree frogs all over my house. Not any trees at that time. We used to leave the porch lights on a lot and they would live off the bugs that was drawn to the light. They would live behind the siding on the house and around the window sills. Don't know where they got their water from at that time. Now with the pond they are all over the pond and it is deafening in the summer with them re-producing. And now I have the Barking Tree Frogs also more and more every year.

Just about any size water container will work. I keep lotus plants in large tubs down to 5 gal buckets. Three or four inches of water is all they need. They ALL had tree frog activity. And, mosquito dunks do not harm the young tadpoles. The frogs only migrated to the tubs from my deck at night during the rains here in Va. One frog lived on top of my outdoor speaker under the eave all summer.
fred

Try sinking a half depth whiskey barrel liner in the ground. You can put potted plants in it and decorate it with rocks.

I have used Mosquito Dunks in all of my ponds for over a decade and have tons of native treefrogs with no problems.

even though the adult frogs are the size of a quarter their tadpoles are significantly larger than mosquito larvae....