Bats & birds won’t solve mosquito problems

By Ruide Xue, Ph.D.

“Should we put up bat/bird houses in our yard or around our subdivision and attractant mosquito-eaters so that they control mosquitoes?”  This is a common question frequently asked by local residents, homeowner associations, and communities looking to encourage mosquito control by natural methods.

Bats/birds eat mosquitoes and are primary predators of vast numbers of insects that fly, and some species consume large numbers of mosquitoes. However, mosquito control is a complex problem that rarely can be solved by a single approach, be it bat/bird houses or pesticides.

So far, neither bats nor birds (purple martins) have ever been shown to solve the mosquito problems. Scientific literatures show that purple martins actually ate very few mosquitoes. One study looked at the stomach contents from 205 birds, not one stomach contained any mosquitoes. Another study checked 34 stomachs, of which only 7 contained mosquitoes and mosquitoes comprised only 3% of the bird’s diet.

Bats/birds may be both opportunistic and selective in their feeding.  Research has shown that bats and birds feed on beetles, moths, flies, midges, mosquitoes, mayflies, and other insects. Most species of bats include a wide variety of insects in their diet and are not selective in consuming only those insects that annoy people, such as mosquitoes.

There are many factors that influence the effectiveness of bats/birds in controlling mosquitoes. Bats/birds feeding and the flight activity of mosquitoes do not coincide with peak mosquito activity times.

Most birds feed during the day, but most mosquitoes are active at night making it unlikely that a bird will encounter a mosquito. Bats feed at night after 10pm , but the species of mosquitoes that is responsible for most complaints by residents are active in the late afternoon and sunset. In St. Johns County , adult mosquito populations rise from May to November, the peak of activity usually appeared during July - September. Actually, bats/birds consume other bugs most of the time, not adult mosquitoes.

Adult mosquitoes are generally sit-and-wait predators and are not flying all the time, so it is very rare that bats/birds are even going to find them. After swarming and mating, the female mosquitoes start to look for warm-blooded hosts for blood meal. When there is not warm-blooded host around, the mosquitoes just hide in the bushes and feed on plant juices and nectar for survival.

A variety of options for mosquito control should be considered. The best way to fight mosquitoes is to control larvae and breeding resources (standing water) in/around your yard and neighborhood. This way is easiest and more effective than hanging a wooden box for bats/birds for controlling mosquitoes.