Lighting up Life for Bats.

Yes I know bats have poor vision but I have seen bats appreciating the illumination provided by electric lights. A lot of years ago now I decided to light up the yard outside the house and to save me the trouble of looking for a switch in the dark I installed a light with a proximity sensor so all I had to do was walk out of the back door and the light came on; great everything worked as planned and as soon as I stepped in front of the light it came on.  Not only did this help me see but it was a great security feature all was well, or so I thought.  We had quite a large population of bats living in the old buildings and they appeared from the cracks every night to hunt the night flying insects.  I like bats, I have always enjoyed watching them in the evening, before it gets too dark.  I find it amazing that they can navigate round objects at such a speed using nothing more than echoes.  Well the proximity switch was sensitive enough to switch the light on as a bat flew past, the trouble was that when the light came on it attracted moths.  The moths attracted more bats which switched the light on more often and this attracted even more moths and other insects so the bats continued to flit around the light keeping it on.  I eventually added an off switch to bypass the sensor.  I felt sorry to be depriving the bats of easy feeding but I didn't like the electricity bill.