Ultrasonic Frequencies...

[Gerald Pollack]

In article <3s7fvj$qjc at fidoii.cc.lehigh.edu> jhs2 at lehigh.edu writes:
>From: jhs2 at lehigh.edu
>Subject: Ultrasonic Frequencies...
>Date: Sun, 18 Jun 95 17:51:29

>I'm looking for ultrasonic frequencies that could be used to deter the presence
>of flies.  Any help would be appreciated.  Please reply to jhs2 at lehigh.edu. 
>Thank you, Joe Schwendt.
Although ultrasonic sensitivity has been reported for one group of flies, most 
can only hear relatively low sound frequencies, in the range of a few 
hundred Hz, and that only at very close range (these 
restrictions have to do with the fact that most flies don't have bona fide 
ears, i.e. devices for detecting rapid variations in air pressure, but instead 
have sensory structures that detect movements of air particles, i.e. 
oscillating winds). Those flies that can hear ultrasound probably use this to 
avoid being eaten by bats, which use ultrasound to detect prey. Different bats 
use different frequencies, but a good ballpark range is 20-50 kHz.