|Lightning beetle flirting with death - Linda Bower|
Measuring two inches, they are elusive unless less you can sneak up on one that is calling. It produces a short trill which you can hear on this MDC link. Gray treefrogs are frequently found on windows as they take advantage of the insects attracted to light.
The "lightning beetle" referred to above is no mistake. They are Coleoptera (beetles), misnamed as bugs or flies just like "lady bugs" and other beetle examples. I was going to expand on fireflies but Bug Lady has beaten me to it in this highly recommended blog posting.