If you think you know where he is...
I usually (while lights on.. early or late, never mid-day) while watching the spot, will make "like" taps with a piece of metal on the acrylic.
Usually two taps...
Within moments I'll usually see his little eyes poking out to see what going on.
BTW, A mantis makes higher pitched click(s) and a pistol makes more of a deeper popping crack sound.
Once you hear the difference, IMO, they're quite distinct.