Going Batty

I've had this idea for photographing some bats that live near Canadice Lake. At dusk, I'd hang a cut apple from tree branch. I think they're insect eaters from the little I've seen of them. I think a cut apple would attract insects. My problem has always been that I don't know where the bats are coming from. I've only seen them once, flying over the lake.
Well, I was dragging the dog out of a thorn bush, when I saw a hollow tree. I couldn't see a thing up in there, so I jammed my camera up the hole, and snapped a couple flash shots. I figured I'd find out what was up there when i got back home. Well, lo and behold, there was a bat up there!
Now that I know where some bats roost, I can put the apple close by. Hopefully, that will increase my chances of getting a good shot. We'll see.