LB – not in the air – on the floor or wall.
actually, I’m not sure if I ever caught a fly, but I probably have. I was thinking more of spiders and mice. I put one cup over it, and then slowly lift it while putting the other cup over the first cup.
I remember a funny incident from when I was in high school. I caught a mouse that way, and I wanted to take it out to the fields right away, but the secretary made me wait till after davening, so I left it on my desk (in the cups). Some of the girls in my class freaked out when they came into the room and saw it. It was really funny!
I don’t know why they were so freaked out – it was safely contained in the cups. And it’s not like it was a scary animal like a dog.