[Twisted_100]

I've seen a lot of people claiming that spiders cannot climb sand/sandstone/glass/whatever. Before you build your entire home out of sandstone hoping that no spider will be able to get in, I'm going to warn you - you're wrong. Spiders can climb everything, even cacti, although climbing cacti makes them fall off immediately.

[cerevox]

cool, never knew that. I just assumed that since glass was immune to everything else, spiders couldn't climb it.

minepedia spider article
http://www.minecraftwiki.net/wiki/Spider