Bats consume a variety of mosquitoes but studies show they are likely a small percentage of their overall diet. Why aren’t bats eating more mosquitoes? Well, they are pretty small, which makes them hard to catch and not very high in calories. A bat flying around at night is probably better off trying to catch a moth or beetle that is larger, which will be easier to catch and provide more energy. Their preference for beetles and moths contributes to their high consumption of agricultural pests which provides valuable ecosystem services.
So what is the solution to mosquitoes?
Make sure you regularly dump any standing water from bird baths, flowerpots, toys, etc. The early life stages of mosquitos depend on water, so this is an easy way to stop eggs from maturing into adults. A bird bath should be changed once a week.
If your gutters aren’t clear, that will cause standing water, so make sure to maintain your gutter system to move water.
If you have standing water on the ground, you can plant some water-loving plants (a rain garden!) that will help soak the water up quickly – Rain gardens offer standing-water solutions | Flowers, Fruits and Frass | Illinois Extension | UIUC
Soak it up: rain gardens and bioswales | Good Growing | Illinois Extension | UIUC
Planting native plants – https://extension.illinois.edu/cfiv/pollinator-pockets will create habitat for a more diverse set of insects, like moths, which bats eat lots of and likely also attract dragonflies that eat mosquitoes.
We recommend avoiding insecticide use as these can have negative impacts on insect eating animals like birds and bats. Also their application becomes less and less effective over time as mosquitos become resistant, requiring higher and higher doses.