Sterile mosquitoes vs bats, birds and mosquitofish
Wildlife eats mosquitoes. Here's how much, and what it means for your yard.
Bats, purple martins and dragonflies do eat mosquitoes, but diet studies show mosquitoes are a small or variable share of what they eat, and no study we found shows a bat house or martin house lowering mosquito numbers in a yard. Mosquitofish eat larvae in ponds, but the Asian tiger and yellow fever mosquitoes that bite in yards breed mostly in small containers fish can't reach. Sterile males are biological control too, and they go after those species directly, safely for people, pets, pollinators and the wildlife you want to keep.
Bats
Bats are some of the best insect hunters at night. Mosquitoes are on the menu, though rarely the main course.
What studies show. DNA testing of droppings from Wisconsin roosts found mosquito DNA in 71.9% of little brown bat samples and 33.3% of big brown bat samples.¹ That tells us how often bats eat mosquitoes, not how many. Other diet studies find mosquitoes make up a small share overall: in five Australian bat species, moths were found in 49 of 52 bats, while mosquitoes showed up in only the two smallest species.²
What it means for a yard. Bat Conservation International, as quoted by Leon County, Florida's mosquito control program, notes that mosquito control "rarely can be solved by a single approach, be it bat houses or pesticides."³ A bat house is good for bats. It isn't a mosquito plan.
1. Wray et al., "Incidence and taxonomic richness of mosquitoes in the diets of little brown and big brown bats," Journal of Mammalogy 99(3): 668-674, 2018, https://www.fs.usda.gov/nrs/pubs/jrnl/2018/nrs_2018_wray_001.pdf 2. Gonsalves et al., "Mosquito consumption by insectivorous bats: does size matter?" PLOS ONE, 2013, https://pmc.ncbi.nlm.nih.gov/articles/PMC3795000/ 3. Leon County, FL, Mosquito Control, "Biological control," https://cms.leoncountyfl.gov/Government/Departments/Public-Works/Operations/Mosquito-Control/Mosquito-Science/Biological-Control
Purple martins
Martin houses are often sold as mosquito control. The diet research doesn't back that up.
The Purple Martin Conservation Association reports that a 3-year diet study at its headquarters found no mosquitoes in 350 diet samples from parent birds feeding their young, as quoted by Leon County, Florida.¹ University of Georgia Extension calls the martin's role in mosquito control "highly overrated."² Martins are wonderful birds to host. They just eat other flying insects, mostly.
1. Purple Martin Conservation Association, quoted by Leon County, FL, Mosquito Control, "Biological control." 2. University of Georgia Cooperative Extension, Circular 977, "Purple martins," https://fieldreport.caes.uga.edu/publications/C977/purple-martins/
Dragonflies
Adult dragonflies catch flying insects, and their water-dwelling young eat larvae. The effect on a yard is unmeasured.
NC State Extension says dragonflies contribute to the natural control of mosquitoes, since both adults and young eat them.¹ Texas A&M AgriLife's dragonfly experts are more cautious: dragonflies are "not likely to be the answer" to a mosquito problem, and they point instead to draining standing water, Bti larvicide in water that can't be drained, and repellent.² We haven't found a study that measures dragonflies lowering mosquito numbers in a yard.
1. NC State Extension, "Dragonfly," Biological Control Information Center, https://entomology.ces.ncsu.edu/biological-control-information-center/beneficial-predators/dragonfly/ 2. Texas A&M AgriLife, "Questions from our readers," https://agrilife.org/dragonfly/questions-from-our-readers/
Mosquitofish
The western mosquitofish, Gambusia affinis, eats mosquito larvae. It's useful in the right pond, with real caveats.
Where it helps. In Texas the fish is native. The University of Texas notes it is the most common and widespread fish in the state.¹ In an ornamental pond or a contained water feature, it can eat larvae that would otherwise hatch.
Where it causes problems. Outside its native range the record is mixed. It has been linked to declines of local frogs and damselflies in places like Hawaii and Arizona, and Australia treats it as a pest.¹ It appears on the IUCN Invasive Species Specialist Group's list of 100 of the world's worst invasive alien species.² Don't release it into creeks, lakes or other natural waters. Ask your county extension office before stocking.
Why it misses yard mosquitoes. The CDC notes that Aedes females lay eggs on the inner walls of containers with water, such as bowls, cups, tires, barrels and vases, and need only a small amount.³ No fish lives in a plant saucer or a clogged gutter.
1. University of Texas at Austin, Biodiversity Center, "Campus biodiversity: western mosquitofish," https://biodiversity.utexas.edu/news/features/campus-biodiversity-western-mosquito-fish 2. Lowe S, et al., "100 of the World's Worst Invasive Alien Species," IUCN Invasive Species Specialist Group, 2000. 3. CDC, "Life cycle of Aedes mosquitoes," April 16, 2024, https://www.cdc.gov/mosquitoes/about/life-cycle-of-aedes-mosquitoes.html
How sterile males work
Instead of hoping a predator finds them, sterile males find the wild females themselves, including where sprays and traps can't reach. Their eggs don't hatch, so the local population collapses, generation by generation. It's biological control that's precisely targeted: it affects only the two mosquito species we release, so bats, birds, fish and dragonflies lose nothing but some mosquitoes.
Four steps to fewer mosquitoes
Side by side
| Compared on | Sterile males (SMF) | Bat houses | Purple martin houses | Dragonflies | Mosquitofish |
|---|---|---|---|---|---|
| Targets yard biters | Yes, the species released | Mixed diet, mostly at night | Rarely eats mosquitoes | Mixed diet | Larvae in ponds only |
| Reaches hidden breeding sites | Yes, males seek out the females | No | No | No | No |
| Measured effect on yard mosquitoes | Published public-program results for the method | No study found | No study found | No study found | Pond only |
| Risk to other wildlife | Only the species released | None | None | None | Invasive outside native range |
| Effort | A release plate twice a month (once a month in winter) | Install and wait | Install, manage, wait | None | Stock and maintain a pond |
When predators are the right choice
Wildlife belongs in a healthy yard, whatever you do about mosquitoes.
- You love bats and birds. Put up the bat house or martin house for them. It supports species that eat moths, beetles and other insects.
- You have a pond. Mosquitofish suit a contained ornamental pond, and they're native here. Bti larvicide is another option for water that can't be drained; see larvicides.
- Your problem is in one pond. If the mosquitoes are breeding in a single water feature, treat that water first.
Using them together
Sterile males and wildlife get along. Releases reduce only the species released, so the other insects bats and birds feed on are untouched.
The CDC states that irradiated mosquitoes cannot make people or animals, including fish, birds and pets, sick.¹ A strong plan for many DFW yards: keep the bat house, stock the pond if you have one, tip out containers weekly, and let sterile males handle the container breeders you'll never find. Prefer plant-based approaches? See sterile males vs natural mosquito control. Safety detail is on our safety page, the method on the science page, and the published results from public programs.
1. CDC, "Irradiated mosquitoes," May 14, 2024, https://www.cdc.gov/mosquitoes/mosquito-control/irradiated-mosquitoes.html
FAQ
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Wray et al., Journal of Mammalogy, 2018. Purple Martin Conservation Association via Leon County, FL. Texas A&M AgriLife.
Do bats eat mosquitoes?
Yes, some do. A Wisconsin study found mosquito DNA in most little brown bat samples. But mosquitoes are usually a small share of a bat's diet, which in diet studies is mostly moths.
Do bat houses help with mosquitoes?
We haven't found a study showing a bat house lowers mosquito numbers in a yard. Bat houses help bats, which is worth doing on its own.
Do purple martins eat mosquitoes?
Rarely. A Purple Martin Conservation Association diet study found no mosquitoes in 350 samples. Martins mostly eat other flying insects.
Do mosquito fish really eat mosquito larvae?
Yes, in ponds and water features. They can't reach the buckets, saucers and gutters where yard mosquitoes mostly breed, and they shouldn't be released into natural waters.
Do dragonflies control mosquitoes?
They eat some, as adults and as young in the water. Texas A&M AgriLife says they're not likely to solve a mosquito problem.
Will fewer mosquitoes hurt bats and birds?
Sterile males reduce only the species released, not the moths, beetles and other insects most bats and birds rely on.
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