Motion/Flood light noise

Didn't think I would be making my second new thread post in the same night. Anyways, I heard a noise outside my house so I go investigate. I was expecting to surprise the raccoon which has been sneaking into the back of my truck for a bag of trash. I just wanted to see the theif. So I didn't find anything.

I decided to walk around the yard and check on the place. One of my motion/flood lights comes on and is make a bug zapper sound real loud. Cutting itself off and on every few seconds. I have never heard a light make that kind of noise. Not a hum, sounds more like a tattoo gun.

Dave