Fly spray.
Turn off the TV and unplug it.
Spray fly spray above and around the TV, but NOT directly at it or into the vents.
Leave for 15 minutes or so.
I used to own a Panasonic 47inch rear projection TV many years ago, one summer it had a spider living in it that would occasionally appear on the inside of the screen. It would also sometimes appear to walk across one of the lamps directly, so would look bloody huge and freaky. Before I gave it away I removed the back of the TV and gave it all a good clean, there was actually a damn web across the inside of the Fresnel screen.