thousands of insects fell and then flew in mass as I placed my ruler near the edge of one area where they were. They swarmed around me, landed on me and made life miserable for a short while as they are noted for a bite that burns and itches for hours and then blisters. I was fortunate as I received no bite and after exiting the room, reentered when they had settled back on the wall. My second attempt on a different group was met with a better outcome.