Mosquito eating bats:

You may have heard the claim that bats eat 600 mosquitoes an hour! But what you may not know is the truth behind this claim. In 1960, D.R. Griffin, F.A. Webster, and C.R. Michael had their study published titled, "The Echolocation of Flying Insects by Bats" in the journal Animal Behavior, 8:141-154. The purpose of this study was to test and observe the echolocation of bats, not their feeding habits. So what better target than something small like mosquitoes to really test the bats ability to find prey?

Methods:

• Only 'proven hunters' were used. The scientists made sure to use bats that they had observed to be active and aggressive hunters for their study.
• The testing room was 8 feet by 16 feet in size, without obstacles to interfere with observing the bats.
• Hunting sessions were only 10-15 minutes in length.
• 2,000 mosquitoes, and only mosquitoes, would be released into the testing room.

Results:

• One bat did achieve capturing 9.5 mosquitoes per minute (average). This same bat on another testing round captured only 1.7 mosquitoes per minute (avg).
• The scientists (in their study) did not list every foraging attempt. They did however record that "On other occasions the same bats gained very little, or even lost weight while flying in the same chamber."
• The one time that one bat achieved the 9.5 mosquitoes per minute capture rate was what was used to later come up with the claim that "bats eat 600 mosquitoes per hour".

Conclusion:

• We definitely agree with the assertion that bats will feed upon mosquitoes, but based upon numerous other studies, we believe it has been shown that bats are opportunistic feeders and are not an effective or reliable form of mosquito control.
• Our concern is the misinformation that comes from taking one sentence out of an entire study and then making wide sweeping assumptions that may affect the publics' perception on what are effective mosquito control tactics.

Purple Martins, Mosquito Eating Machines, or Salesman's Hook:

Another popular myth is that Purple Martins eat extremely large numbers of mosquitoes daily. The Purple Martin Conservation Society addresses this issue at their website: Purple Martins> Species Profile; Food, where it states, "However Purple Martins do not eat a large number of mosquitoes.  Martins feed high in the sky during the daytime, so they do not come into contact with mosquitoes very often."

Summary:

A review of the pertinent scientific and popular ornithological literature leads to the following conclusions:

• Mosquitoes appear to be a negligible item in the diet of the Purple Martin.
• Behavior patterns of mosquitoes and martins are such that most mosquitoes are not flying in martin feeding areas when martins are active; contact between the two is minimal during day light hours.
• None of the published statements appearing in the popular or ethnological literature that attribute a mosquito-feeding habit to the Purple Martin are based on a factual study; the oft-quoted statement "a martin eats 2,000 mosquitoes per day" has no evident means of support.
• No evidence exists that any avian species can effectively control a species of insect pest upon which it feeds when that pest is at or near peak abundance.
• The Purple Martin is one of our most beautiful and friendly birds. It daily consumes a large number of insects. Its aesthetic qualities alone recommend it highly to man. There is no need to ascribe to the martin abilities greater than those it already possesses in order to encourage its protection and propagation.