This isn't about spiders, but cockroaches - I once heard of a cellist who was taking part in a concert with her string quartet. They were up on stage, playing away, when the cellist spotted a cockroach on the stage floor and it was coming towards her. She couldn't do anything about it and she just had to keep on playing. Unfortunately, it wasn't put off by her long skirt and just crawled underneath the hem and up her leg!!!! And as the show had to go on, she still just had to keep on playing!! (This was told me by someone who knew her.)